* [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm
@ 2022-02-14 10:44 syzbot
2022-02-14 19:07 ` Yang Shi
0 siblings, 1 reply; 9+ messages in thread
From: syzbot @ 2022-02-14 10:44 UTC (permalink / raw)
To: akpm, brauner, linux-kernel, linux-mm, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: e6251ab4551f Merge tag 'nfs-for-5.17-2' of git://git.linux..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1229b2f8700000
kernel config: https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45
dashboard link: https://syzkaller.appspot.com/bug?extid=2ccf63a4bd07cf39cab0
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386
Unfortunately, I don't have any reproducer for this issue yet.
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: use-after-free in can_madv_lru_vma mm/internal.h:76 [inline]
BUG: KASAN: use-after-free in __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529
Read of size 8 at addr ffff88807b868ba8 by task syz-executor.2/12778
CPU: 0 PID: 12778 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00029-ge6251ab4551f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
can_madv_lru_vma mm/internal.h:76 [inline]
__oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529
__do_sys_process_mrelease+0x3f2/0x450 mm/oom_kill.c:1196
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf6e70549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f586a5cc EFLAGS: 00000296 ORIG_RAX: 00000000000001c0
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Allocated by task 12778:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
__kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469
kasan_slab_alloc include/linux/kasan.h:260 [inline]
slab_post_alloc_hook mm/slab.h:732 [inline]
slab_alloc_node mm/slub.c:3230 [inline]
slab_alloc mm/slub.c:3238 [inline]
kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243
vm_area_dup+0x88/0x2b0 kernel/fork.c:357
dup_mmap kernel/fork.c:554 [inline]
dup_mm+0x5fa/0x13e0 kernel/fork.c:1451
copy_mm kernel/fork.c:1503 [inline]
copy_process+0x71f8/0x7300 kernel/fork.c:2164
kernel_clone+0xe7/0xab0 kernel/fork.c:2555
__do_compat_sys_ia32_clone+0xac/0xe0 arch/x86/kernel/sys_ia32.c:254
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
Freed by task 12780:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:236 [inline]
slab_free_hook mm/slub.c:1728 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754
slab_free mm/slub.c:3509 [inline]
kmem_cache_free+0xd8/0x340 mm/slub.c:3526
remove_vma+0x135/0x170 mm/mmap.c:189
exit_mmap+0x29a/0x670 mm/mmap.c:3186
__mmput+0x122/0x4b0 kernel/fork.c:1114
mmput+0x56/0x60 kernel/fork.c:1135
exit_mm kernel/exit.c:507 [inline]
do_exit+0xa3c/0x2a30 kernel/exit.c:793
do_group_exit+0xd2/0x2f0 kernel/exit.c:935
get_signal+0x4b0/0x28c0 kernel/signal.c:2862
arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
__do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181
do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
The buggy address belongs to the object at ffff88807b868b58
which belongs to the cache vm_area_struct of size 200
The buggy address is located 80 bytes inside of
200-byte region [ffff88807b868b58, ffff88807b868c20)
The buggy address belongs to the page:
page:ffffea0001ee1a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b868
memcg:ffff88804fe94a01
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888140006a00
raw: 0000000000000000 00000000000f000f 00000001ffffffff ffff88804fe94a01
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 3175, ts 344170603641, free_ts 344164018467
prep_new_page mm/page_alloc.c:2434 [inline]
get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271
alloc_slab_page mm/slub.c:1799 [inline]
allocate_slab mm/slub.c:1944 [inline]
new_slab+0x28a/0x3b0 mm/slub.c:2004
___slab_alloc+0x87c/0xe90 mm/slub.c:3018
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105
slab_alloc_node mm/slub.c:3196 [inline]
slab_alloc mm/slub.c:3238 [inline]
kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3243
vm_area_dup+0x88/0x2b0 kernel/fork.c:357
dup_mmap kernel/fork.c:554 [inline]
dup_mm+0x5fa/0x13e0 kernel/fork.c:1451
copy_mm kernel/fork.c:1503 [inline]
copy_process+0x71f8/0x7300 kernel/fork.c:2164
kernel_clone+0xe7/0xab0 kernel/fork.c:2555
__do_sys_clone+0xc8/0x110 kernel/fork.c:2672
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1352 [inline]
free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404
free_unref_page_prepare mm/page_alloc.c:3325 [inline]
free_unref_page_list+0x1a9/0xfa0 mm/page_alloc.c:3441
release_pages+0x317/0x1220 mm/swap.c:980
tlb_batch_pages_flush mm/mmu_gather.c:50 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:243 [inline]
tlb_flush_mmu mm/mmu_gather.c:250 [inline]
tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:341
exit_mmap+0x21b/0x670 mm/mmap.c:3180
__mmput+0x122/0x4b0 kernel/fork.c:1114
mmput+0x56/0x60 kernel/fork.c:1135
exit_mm kernel/exit.c:507 [inline]
do_exit+0xa3c/0x2a30 kernel/exit.c:793
do_group_exit+0xd2/0x2f0 kernel/exit.c:935
get_signal+0x4b0/0x28c0 kernel/signal.c:2862
arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
__do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181
do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
Memory state around the buggy address:
ffff88807b868a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807b868b00: fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb
>ffff88807b868b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807b868c00: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb
ffff88807b868c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi
4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d
a: 10 06 adc %al,(%rsi)
c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
10: 10 07 adc %al,(%rdi)
12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
16: 10 08 adc %cl,(%rax)
18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
1c: 00 00 add %al,(%rax)
1e: 00 00 add %al,(%rax)
20: 00 51 52 add %dl,0x52(%rcx)
23: 55 push %rbp
24: 89 e5 mov %esp,%ebp
26: 0f 34 sysenter
28: cd 80 int $0x80
* 2a: 5d pop %rbp <-- trapping instruction
2b: 5a pop %rdx
2c: 59 pop %rcx
2d: c3 retq
2e: 90 nop
2f: 90 nop
30: 90 nop
31: 90 nop
32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
---
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^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-14 10:44 [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm syzbot @ 2022-02-14 19:07 ` Yang Shi 2022-02-15 9:59 ` Michal Hocko 0 siblings, 1 reply; 9+ messages in thread From: Yang Shi @ 2022-02-14 19:07 UTC (permalink / raw) To: syzbot Cc: Andrew Morton, brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs On Mon, Feb 14, 2022 at 2:44 AM syzbot <syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: e6251ab4551f Merge tag 'nfs-for-5.17-2' of git://git.linux.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1229b2f8700000 > kernel config: https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45 > dashboard link: https://syzkaller.appspot.com/bug?extid=2ccf63a4bd07cf39cab0 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > userspace arch: i386 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com > > ================================================================== > BUG: KASAN: use-after-free in can_madv_lru_vma mm/internal.h:76 [inline] > BUG: KASAN: use-after-free in __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > Read of size 8 at addr ffff88807b868ba8 by task syz-executor.2/12778 > > CPU: 0 PID: 12778 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00029-ge6251ab4551f #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255 > __kasan_report mm/kasan/report.c:442 [inline] > kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 > can_madv_lru_vma mm/internal.h:76 [inline] > __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > __do_sys_process_mrelease+0x3f2/0x450 mm/oom_kill.c:1196 > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > RIP: 0023:0xf6e70549 > Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > RSP: 002b:00000000f586a5cc EFLAGS: 00000296 ORIG_RAX: 00000000000001c0 > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > </TASK> > > Allocated by task 12778: > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > kasan_set_track mm/kasan/common.c:45 [inline] > set_alloc_info mm/kasan/common.c:436 [inline] > __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 > kasan_slab_alloc include/linux/kasan.h:260 [inline] > slab_post_alloc_hook mm/slab.h:732 [inline] > slab_alloc_node mm/slub.c:3230 [inline] > slab_alloc mm/slub.c:3238 [inline] > kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243 > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > dup_mmap kernel/fork.c:554 [inline] > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > copy_mm kernel/fork.c:1503 [inline] > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > __do_compat_sys_ia32_clone+0xac/0xe0 arch/x86/kernel/sys_ia32.c:254 > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > Freed by task 12780: > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > kasan_set_track+0x21/0x30 mm/kasan/common.c:45 > kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 > ____kasan_slab_free mm/kasan/common.c:366 [inline] > ____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328 > kasan_slab_free include/linux/kasan.h:236 [inline] > slab_free_hook mm/slub.c:1728 [inline] > slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754 > slab_free mm/slub.c:3509 [inline] > kmem_cache_free+0xd8/0x340 mm/slub.c:3526 > remove_vma+0x135/0x170 mm/mmap.c:189 > exit_mmap+0x29a/0x670 mm/mmap.c:3186 > __mmput+0x122/0x4b0 kernel/fork.c:1114 > mmput+0x56/0x60 kernel/fork.c:1135 > exit_mm kernel/exit.c:507 [inline] > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > handle_signal_work kernel/entry/common.c:148 [inline] > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c It seems process_mrelease() may be racy with exiting. mmgrab() just pin mm struct, but doesn't guarantee the associated address space still exists. mmget or mmget_not_zero() may be needed at first glance. The below untested patch (compiled) may be able to fix it. diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 832fb330376e..c389995bcc71 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -1185,9 +1185,11 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags) if (!reap) goto drop_mm; + if (!mmget_not_zero(mm)) + goto drop_mm; if (mmap_read_lock_killable(mm)) { ret = -EINTR; - goto drop_mm; + goto put_mm; } /* * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure @@ -1197,6 +1199,8 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags) ret = -EAGAIN; mmap_read_unlock(mm); +put_mm: + mmput(mm); drop_mm: mmdrop(mm); put_task: > > The buggy address belongs to the object at ffff88807b868b58 > which belongs to the cache vm_area_struct of size 200 > The buggy address is located 80 bytes inside of > 200-byte region [ffff88807b868b58, ffff88807b868c20) > The buggy address belongs to the page: > page:ffffea0001ee1a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b868 > memcg:ffff88804fe94a01 > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888140006a00 > raw: 0000000000000000 00000000000f000f 00000001ffffffff ffff88804fe94a01 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 3175, ts 344170603641, free_ts 344164018467 > prep_new_page mm/page_alloc.c:2434 [inline] > get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165 > __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389 > alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271 > alloc_slab_page mm/slub.c:1799 [inline] > allocate_slab mm/slub.c:1944 [inline] > new_slab+0x28a/0x3b0 mm/slub.c:2004 > ___slab_alloc+0x87c/0xe90 mm/slub.c:3018 > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 > slab_alloc_node mm/slub.c:3196 [inline] > slab_alloc mm/slub.c:3238 [inline] > kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3243 > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > dup_mmap kernel/fork.c:554 [inline] > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > copy_mm kernel/fork.c:1503 [inline] > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > __do_sys_clone+0xc8/0x110 kernel/fork.c:2672 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > page last free stack trace: > reset_page_owner include/linux/page_owner.h:24 [inline] > free_pages_prepare mm/page_alloc.c:1352 [inline] > free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404 > free_unref_page_prepare mm/page_alloc.c:3325 [inline] > free_unref_page_list+0x1a9/0xfa0 mm/page_alloc.c:3441 > release_pages+0x317/0x1220 mm/swap.c:980 > tlb_batch_pages_flush mm/mmu_gather.c:50 [inline] > tlb_flush_mmu_free mm/mmu_gather.c:243 [inline] > tlb_flush_mmu mm/mmu_gather.c:250 [inline] > tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:341 > exit_mmap+0x21b/0x670 mm/mmap.c:3180 > __mmput+0x122/0x4b0 kernel/fork.c:1114 > mmput+0x56/0x60 kernel/fork.c:1135 > exit_mm kernel/exit.c:507 [inline] > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > handle_signal_work kernel/entry/common.c:148 [inline] > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > Memory state around the buggy address: > ffff88807b868a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff88807b868b00: fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb > >ffff88807b868b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff88807b868c00: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb > ffff88807b868c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > ---------------- > Code disassembly (best guess): > 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi > 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d > a: 10 06 adc %al,(%rsi) > c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi > 10: 10 07 adc %al,(%rdi) > 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi > 16: 10 08 adc %cl,(%rax) > 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi > 1c: 00 00 add %al,(%rax) > 1e: 00 00 add %al,(%rax) > 20: 00 51 52 add %dl,0x52(%rcx) > 23: 55 push %rbp > 24: 89 e5 mov %esp,%ebp > 26: 0f 34 sysenter > 28: cd 80 int $0x80 > * 2a: 5d pop %rbp <-- trapping instruction > 2b: 5a pop %rdx > 2c: 59 pop %rcx > 2d: c3 retq > 2e: 90 nop > 2f: 90 nop > 30: 90 nop > 31: 90 nop > 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-14 19:07 ` Yang Shi @ 2022-02-15 9:59 ` Michal Hocko 2022-02-15 17:34 ` Suren Baghdasaryan 0 siblings, 1 reply; 9+ messages in thread From: Michal Hocko @ 2022-02-15 9:59 UTC (permalink / raw) To: Yang Shi, Suren Baghdasaryan Cc: syzbot, Andrew Morton, brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs [Add Suren - and keeping the full message for reference. My comment in inlined] On Mon 14-02-22 11:07:05, Yang Shi wrote: > On Mon, Feb 14, 2022 at 2:44 AM syzbot > <syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com> wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: e6251ab4551f Merge tag 'nfs-for-5.17-2' of git://git.linux.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=1229b2f8700000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45 > > dashboard link: https://syzkaller.appspot.com/bug?extid=2ccf63a4bd07cf39cab0 > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > userspace arch: i386 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com > > > > ================================================================== > > BUG: KASAN: use-after-free in can_madv_lru_vma mm/internal.h:76 [inline] > > BUG: KASAN: use-after-free in __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > Read of size 8 at addr ffff88807b868ba8 by task syz-executor.2/12778 > > > > CPU: 0 PID: 12778 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00029-ge6251ab4551f #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > Call Trace: > > <TASK> > > __dump_stack lib/dump_stack.c:88 [inline] > > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > > print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255 > > __kasan_report mm/kasan/report.c:442 [inline] > > kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 > > can_madv_lru_vma mm/internal.h:76 [inline] > > __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > __do_sys_process_mrelease+0x3f2/0x450 mm/oom_kill.c:1196 > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > RIP: 0023:0xf6e70549 > > Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > > RSP: 002b:00000000f586a5cc EFLAGS: 00000296 ORIG_RAX: 00000000000001c0 > > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000 > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > </TASK> > > > > Allocated by task 12778: > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > kasan_set_track mm/kasan/common.c:45 [inline] > > set_alloc_info mm/kasan/common.c:436 [inline] > > __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 > > kasan_slab_alloc include/linux/kasan.h:260 [inline] > > slab_post_alloc_hook mm/slab.h:732 [inline] > > slab_alloc_node mm/slub.c:3230 [inline] > > slab_alloc mm/slub.c:3238 [inline] > > kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243 > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > dup_mmap kernel/fork.c:554 [inline] > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > copy_mm kernel/fork.c:1503 [inline] > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > __do_compat_sys_ia32_clone+0xac/0xe0 arch/x86/kernel/sys_ia32.c:254 > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > Freed by task 12780: > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > kasan_set_track+0x21/0x30 mm/kasan/common.c:45 > > kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 > > ____kasan_slab_free mm/kasan/common.c:366 [inline] > > ____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328 > > kasan_slab_free include/linux/kasan.h:236 [inline] > > slab_free_hook mm/slub.c:1728 [inline] > > slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754 > > slab_free mm/slub.c:3509 [inline] > > kmem_cache_free+0xd8/0x340 mm/slub.c:3526 > > remove_vma+0x135/0x170 mm/mmap.c:189 > > exit_mmap+0x29a/0x670 mm/mmap.c:3186 > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > mmput+0x56/0x60 kernel/fork.c:1135 > > exit_mm kernel/exit.c:507 [inline] > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > handle_signal_work kernel/entry/common.c:148 [inline] > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > It seems process_mrelease() may be racy with exiting. mmgrab() just > pin mm struct, but doesn't guarantee the associated address space > still exists. mmget or mmget_not_zero() may be needed at first glance. This is what process_mrelease used to do before ba535c1caf3e ("mm/oom_kill: allow process_mrelease to run under mmap_lock protection"). It shouldn't be really necessary because of the synchronization that happens on the exit_mmap level. There were some patches in that area and I am not sure whether something is still hanging in the Andrew's queue. Suren will surely know better. > The below untested patch (compiled) may be able to fix it. > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 832fb330376e..c389995bcc71 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -1185,9 +1185,11 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > unsigned int, flags) > if (!reap) > goto drop_mm; > > + if (!mmget_not_zero(mm)) > + goto drop_mm; > if (mmap_read_lock_killable(mm)) { > ret = -EINTR; > - goto drop_mm; > + goto put_mm; > } > /* > * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure > @@ -1197,6 +1199,8 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > unsigned int, flags) > ret = -EAGAIN; > mmap_read_unlock(mm); > > +put_mm: > + mmput(mm); > drop_mm: > mmdrop(mm); > put_task: > > > > > The buggy address belongs to the object at ffff88807b868b58 > > which belongs to the cache vm_area_struct of size 200 > > The buggy address is located 80 bytes inside of > > 200-byte region [ffff88807b868b58, ffff88807b868c20) > > The buggy address belongs to the page: > > page:ffffea0001ee1a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b868 > > memcg:ffff88804fe94a01 > > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > > raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888140006a00 > > raw: 0000000000000000 00000000000f000f 00000001ffffffff ffff88804fe94a01 > > page dumped because: kasan: bad access detected > > page_owner tracks the page as allocated > > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 3175, ts 344170603641, free_ts 344164018467 > > prep_new_page mm/page_alloc.c:2434 [inline] > > get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165 > > __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389 > > alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271 > > alloc_slab_page mm/slub.c:1799 [inline] > > allocate_slab mm/slub.c:1944 [inline] > > new_slab+0x28a/0x3b0 mm/slub.c:2004 > > ___slab_alloc+0x87c/0xe90 mm/slub.c:3018 > > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 > > slab_alloc_node mm/slub.c:3196 [inline] > > slab_alloc mm/slub.c:3238 [inline] > > kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3243 > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > dup_mmap kernel/fork.c:554 [inline] > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > copy_mm kernel/fork.c:1503 [inline] > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > __do_sys_clone+0xc8/0x110 kernel/fork.c:2672 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > page last free stack trace: > > reset_page_owner include/linux/page_owner.h:24 [inline] > > free_pages_prepare mm/page_alloc.c:1352 [inline] > > free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404 > > free_unref_page_prepare mm/page_alloc.c:3325 [inline] > > free_unref_page_list+0x1a9/0xfa0 mm/page_alloc.c:3441 > > release_pages+0x317/0x1220 mm/swap.c:980 > > tlb_batch_pages_flush mm/mmu_gather.c:50 [inline] > > tlb_flush_mmu_free mm/mmu_gather.c:243 [inline] > > tlb_flush_mmu mm/mmu_gather.c:250 [inline] > > tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:341 > > exit_mmap+0x21b/0x670 mm/mmap.c:3180 > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > mmput+0x56/0x60 kernel/fork.c:1135 > > exit_mm kernel/exit.c:507 [inline] > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > handle_signal_work kernel/entry/common.c:148 [inline] > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > Memory state around the buggy address: > > ffff88807b868a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff88807b868b00: fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb > > >ffff88807b868b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > > ffff88807b868c00: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb > > ffff88807b868c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ================================================================== > > ---------------- > > Code disassembly (best guess): > > 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi > > 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d > > a: 10 06 adc %al,(%rsi) > > c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi > > 10: 10 07 adc %al,(%rdi) > > 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi > > 16: 10 08 adc %cl,(%rax) > > 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi > > 1c: 00 00 add %al,(%rax) > > 1e: 00 00 add %al,(%rax) > > 20: 00 51 52 add %dl,0x52(%rcx) > > 23: 55 push %rbp > > 24: 89 e5 mov %esp,%ebp > > 26: 0f 34 sysenter > > 28: cd 80 int $0x80 > > * 2a: 5d pop %rbp <-- trapping instruction > > 2b: 5a pop %rdx > > 2c: 59 pop %rcx > > 2d: c3 retq > > 2e: 90 nop > > 2f: 90 nop > > 30: 90 nop > > 31: 90 nop > > 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > > > > --- > > This report is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-15 9:59 ` Michal Hocko @ 2022-02-15 17:34 ` Suren Baghdasaryan 2022-02-15 17:53 ` Yang Shi 0 siblings, 1 reply; 9+ messages in thread From: Suren Baghdasaryan @ 2022-02-15 17:34 UTC (permalink / raw) To: Michal Hocko Cc: Yang Shi, syzbot, Andrew Morton, Christian Brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs -> On Tue, Feb 15, 2022 at 1:59 AM Michal Hocko <mhocko@suse.com> wrote: > > [Add Suren - and keeping the full message for reference. My comment in > inlined] > > On Mon 14-02-22 11:07:05, Yang Shi wrote: > > On Mon, Feb 14, 2022 at 2:44 AM syzbot > > <syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com> wrote: > > > > > > Hello, > > > > > > syzbot found the following issue on: > > > > > > HEAD commit: e6251ab4551f Merge tag 'nfs-for-5.17-2' of git://git.linux.. > > > git tree: upstream > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1229b2f8700000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=2ccf63a4bd07cf39cab0 > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > userspace arch: i386 > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com > > > > > > ================================================================== > > > BUG: KASAN: use-after-free in can_madv_lru_vma mm/internal.h:76 [inline] > > > BUG: KASAN: use-after-free in __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > > Read of size 8 at addr ffff88807b868ba8 by task syz-executor.2/12778 > > > > > > CPU: 0 PID: 12778 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00029-ge6251ab4551f #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > > Call Trace: > > > <TASK> > > > __dump_stack lib/dump_stack.c:88 [inline] > > > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > > > print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255 > > > __kasan_report mm/kasan/report.c:442 [inline] > > > kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 > > > can_madv_lru_vma mm/internal.h:76 [inline] > > > __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > > __do_sys_process_mrelease+0x3f2/0x450 mm/oom_kill.c:1196 > > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > RIP: 0023:0xf6e70549 > > > Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > > > RSP: 002b:00000000f586a5cc EFLAGS: 00000296 ORIG_RAX: 00000000000001c0 > > > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000 > > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > > </TASK> > > > > > > Allocated by task 12778: > > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > > kasan_set_track mm/kasan/common.c:45 [inline] > > > set_alloc_info mm/kasan/common.c:436 [inline] > > > __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 > > > kasan_slab_alloc include/linux/kasan.h:260 [inline] > > > slab_post_alloc_hook mm/slab.h:732 [inline] > > > slab_alloc_node mm/slub.c:3230 [inline] > > > slab_alloc mm/slub.c:3238 [inline] > > > kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243 > > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > > dup_mmap kernel/fork.c:554 [inline] > > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > > copy_mm kernel/fork.c:1503 [inline] > > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > > __do_compat_sys_ia32_clone+0xac/0xe0 arch/x86/kernel/sys_ia32.c:254 > > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > Freed by task 12780: > > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > > kasan_set_track+0x21/0x30 mm/kasan/common.c:45 > > > kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 > > > ____kasan_slab_free mm/kasan/common.c:366 [inline] > > > ____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328 > > > kasan_slab_free include/linux/kasan.h:236 [inline] > > > slab_free_hook mm/slub.c:1728 [inline] > > > slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754 > > > slab_free mm/slub.c:3509 [inline] > > > kmem_cache_free+0xd8/0x340 mm/slub.c:3526 > > > remove_vma+0x135/0x170 mm/mmap.c:189 > > > exit_mmap+0x29a/0x670 mm/mmap.c:3186 > > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > > mmput+0x56/0x60 kernel/fork.c:1135 > > > exit_mm kernel/exit.c:507 [inline] > > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > > handle_signal_work kernel/entry/common.c:148 [inline] > > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > It seems process_mrelease() may be racy with exiting. mmgrab() just > > pin mm struct, but doesn't guarantee the associated address space > > still exists. mmget or mmget_not_zero() may be needed at first glance. > > This is what process_mrelease used to do before ba535c1caf3e > ("mm/oom_kill: allow process_mrelease to run under mmap_lock > protection"). It shouldn't be really necessary because of the > synchronization that happens on the exit_mmap level. There were some > patches in that area and I am not sure whether something is still > hanging in the Andrew's queue. Suren will surely know better. Correct, the proposed change is what we were doing before 64591e8605d6 ("mm: protect free_pgtables with mmap_lock write lock in exit_mmap") and ba535c1caf3e ("mm/oom_kill: allow process_mrelease to run under mmap_lock protection"). The first patch changed exit_mmap to call unlock_range, free_pgtables and remove_vma under mmap_write_lock and the second patch calls __oom_reap_task_mm under mmap_read_lock. From the call stack IIUC __oom_reap_task_mm at https://elixir.bootlin.com/linux/v5.17-rc4/source/mm/oom_kill.c#L1196 is racing with remove_vma at https://elixir.bootlin.com/linux/v5.17-rc4/source/mm/mmap.c#L3186. The mmap_lock should prevent this race and I don't see anything missing in Andrew's tree. I'll go over the code again and re-check but so far I don't see how this race could occur. > > > The below untested patch (compiled) may be able to fix it. > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > index 832fb330376e..c389995bcc71 100644 > > --- a/mm/oom_kill.c > > +++ b/mm/oom_kill.c > > @@ -1185,9 +1185,11 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > > unsigned int, flags) > > if (!reap) > > goto drop_mm; > > > > + if (!mmget_not_zero(mm)) > > + goto drop_mm; > > if (mmap_read_lock_killable(mm)) { > > ret = -EINTR; > > - goto drop_mm; > > + goto put_mm; > > } > > /* > > * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure > > @@ -1197,6 +1199,8 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > > unsigned int, flags) > > ret = -EAGAIN; > > mmap_read_unlock(mm); > > > > +put_mm: > > + mmput(mm); > > drop_mm: > > mmdrop(mm); > > put_task: > > > > > > > > The buggy address belongs to the object at ffff88807b868b58 > > > which belongs to the cache vm_area_struct of size 200 > > > The buggy address is located 80 bytes inside of > > > 200-byte region [ffff88807b868b58, ffff88807b868c20) > > > The buggy address belongs to the page: > > > page:ffffea0001ee1a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b868 > > > memcg:ffff88804fe94a01 > > > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > > > raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888140006a00 > > > raw: 0000000000000000 00000000000f000f 00000001ffffffff ffff88804fe94a01 > > > page dumped because: kasan: bad access detected > > > page_owner tracks the page as allocated > > > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 3175, ts 344170603641, free_ts 344164018467 > > > prep_new_page mm/page_alloc.c:2434 [inline] > > > get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165 > > > __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389 > > > alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271 > > > alloc_slab_page mm/slub.c:1799 [inline] > > > allocate_slab mm/slub.c:1944 [inline] > > > new_slab+0x28a/0x3b0 mm/slub.c:2004 > > > ___slab_alloc+0x87c/0xe90 mm/slub.c:3018 > > > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 > > > slab_alloc_node mm/slub.c:3196 [inline] > > > slab_alloc mm/slub.c:3238 [inline] > > > kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3243 > > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > > dup_mmap kernel/fork.c:554 [inline] > > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > > copy_mm kernel/fork.c:1503 [inline] > > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > > __do_sys_clone+0xc8/0x110 kernel/fork.c:2672 > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > page last free stack trace: > > > reset_page_owner include/linux/page_owner.h:24 [inline] > > > free_pages_prepare mm/page_alloc.c:1352 [inline] > > > free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404 > > > free_unref_page_prepare mm/page_alloc.c:3325 [inline] > > > free_unref_page_list+0x1a9/0xfa0 mm/page_alloc.c:3441 > > > release_pages+0x317/0x1220 mm/swap.c:980 > > > tlb_batch_pages_flush mm/mmu_gather.c:50 [inline] > > > tlb_flush_mmu_free mm/mmu_gather.c:243 [inline] > > > tlb_flush_mmu mm/mmu_gather.c:250 [inline] > > > tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:341 > > > exit_mmap+0x21b/0x670 mm/mmap.c:3180 > > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > > mmput+0x56/0x60 kernel/fork.c:1135 > > > exit_mm kernel/exit.c:507 [inline] > > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > > handle_signal_work kernel/entry/common.c:148 [inline] > > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > Memory state around the buggy address: > > > ffff88807b868a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > ffff88807b868b00: fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb > > > >ffff88807b868b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > ^ > > > ffff88807b868c00: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb > > > ffff88807b868c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > ================================================================== > > > ---------------- > > > Code disassembly (best guess): > > > 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi > > > 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d > > > a: 10 06 adc %al,(%rsi) > > > c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi > > > 10: 10 07 adc %al,(%rdi) > > > 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi > > > 16: 10 08 adc %cl,(%rax) > > > 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi > > > 1c: 00 00 add %al,(%rax) > > > 1e: 00 00 add %al,(%rax) > > > 20: 00 51 52 add %dl,0x52(%rcx) > > > 23: 55 push %rbp > > > 24: 89 e5 mov %esp,%ebp > > > 26: 0f 34 sysenter > > > 28: cd 80 int $0x80 > > > * 2a: 5d pop %rbp <-- trapping instruction > > > 2b: 5a pop %rdx > > > 2c: 59 pop %rcx > > > 2d: c3 retq > > > 2e: 90 nop > > > 2f: 90 nop > > > 30: 90 nop > > > 31: 90 nop > > > 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > > > > > > > --- > > > This report is generated by a bot. It may contain errors. > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > syzbot will keep track of this issue. See: > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > > -- > Michal Hocko > SUSE Labs ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-15 17:34 ` Suren Baghdasaryan @ 2022-02-15 17:53 ` Yang Shi 2022-02-15 18:10 ` Suren Baghdasaryan 0 siblings, 1 reply; 9+ messages in thread From: Yang Shi @ 2022-02-15 17:53 UTC (permalink / raw) To: Suren Baghdasaryan Cc: Michal Hocko, syzbot, Andrew Morton, Christian Brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs On Tue, Feb 15, 2022 at 9:34 AM Suren Baghdasaryan <surenb@google.com> wrote: > > -> > On Tue, Feb 15, 2022 at 1:59 AM Michal Hocko <mhocko@suse.com> wrote: > > > > [Add Suren - and keeping the full message for reference. My comment in > > inlined] > > > > On Mon 14-02-22 11:07:05, Yang Shi wrote: > > > On Mon, Feb 14, 2022 at 2:44 AM syzbot > > > <syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com> wrote: > > > > > > > > Hello, > > > > > > > > syzbot found the following issue on: > > > > > > > > HEAD commit: e6251ab4551f Merge tag 'nfs-for-5.17-2' of git://git.linux.. > > > > git tree: upstream > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1229b2f8700000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45 > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=2ccf63a4bd07cf39cab0 > > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > userspace arch: i386 > > > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com > > > > > > > > ================================================================== > > > > BUG: KASAN: use-after-free in can_madv_lru_vma mm/internal.h:76 [inline] > > > > BUG: KASAN: use-after-free in __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > > > Read of size 8 at addr ffff88807b868ba8 by task syz-executor.2/12778 > > > > > > > > CPU: 0 PID: 12778 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00029-ge6251ab4551f #0 > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > > > Call Trace: > > > > <TASK> > > > > __dump_stack lib/dump_stack.c:88 [inline] > > > > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > > > > print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255 > > > > __kasan_report mm/kasan/report.c:442 [inline] > > > > kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 > > > > can_madv_lru_vma mm/internal.h:76 [inline] > > > > __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > > > __do_sys_process_mrelease+0x3f2/0x450 mm/oom_kill.c:1196 > > > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > RIP: 0023:0xf6e70549 > > > > Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > > > > RSP: 002b:00000000f586a5cc EFLAGS: 00000296 ORIG_RAX: 00000000000001c0 > > > > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000 > > > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > > > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > > > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > > > </TASK> > > > > > > > > Allocated by task 12778: > > > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > > > kasan_set_track mm/kasan/common.c:45 [inline] > > > > set_alloc_info mm/kasan/common.c:436 [inline] > > > > __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 > > > > kasan_slab_alloc include/linux/kasan.h:260 [inline] > > > > slab_post_alloc_hook mm/slab.h:732 [inline] > > > > slab_alloc_node mm/slub.c:3230 [inline] > > > > slab_alloc mm/slub.c:3238 [inline] > > > > kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243 > > > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > > > dup_mmap kernel/fork.c:554 [inline] > > > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > > > copy_mm kernel/fork.c:1503 [inline] > > > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > > > __do_compat_sys_ia32_clone+0xac/0xe0 arch/x86/kernel/sys_ia32.c:254 > > > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > > > Freed by task 12780: > > > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > > > kasan_set_track+0x21/0x30 mm/kasan/common.c:45 > > > > kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 > > > > ____kasan_slab_free mm/kasan/common.c:366 [inline] > > > > ____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328 > > > > kasan_slab_free include/linux/kasan.h:236 [inline] > > > > slab_free_hook mm/slub.c:1728 [inline] > > > > slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754 > > > > slab_free mm/slub.c:3509 [inline] > > > > kmem_cache_free+0xd8/0x340 mm/slub.c:3526 > > > > remove_vma+0x135/0x170 mm/mmap.c:189 > > > > exit_mmap+0x29a/0x670 mm/mmap.c:3186 > > > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > > > mmput+0x56/0x60 kernel/fork.c:1135 > > > > exit_mm kernel/exit.c:507 [inline] > > > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > > > handle_signal_work kernel/entry/common.c:148 [inline] > > > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > It seems process_mrelease() may be racy with exiting. mmgrab() just > > > pin mm struct, but doesn't guarantee the associated address space > > > still exists. mmget or mmget_not_zero() may be needed at first glance. > > > > This is what process_mrelease used to do before ba535c1caf3e > > ("mm/oom_kill: allow process_mrelease to run under mmap_lock > > protection"). It shouldn't be really necessary because of the > > synchronization that happens on the exit_mmap level. There were some > > patches in that area and I am not sure whether something is still > > hanging in the Andrew's queue. Suren will surely know better. > > Correct, the proposed change is what we were doing before 64591e8605d6 > ("mm: protect free_pgtables with mmap_lock write lock in exit_mmap") > and ba535c1caf3e ("mm/oom_kill: allow process_mrelease to run under > mmap_lock protection"). The first patch changed exit_mmap to call > unlock_range, free_pgtables and remove_vma under mmap_write_lock and > the second patch calls __oom_reap_task_mm under mmap_read_lock. From > the call stack IIUC __oom_reap_task_mm at > https://elixir.bootlin.com/linux/v5.17-rc4/source/mm/oom_kill.c#L1196 > is racing with remove_vma at > https://elixir.bootlin.com/linux/v5.17-rc4/source/mm/mmap.c#L3186. The > mmap_lock should prevent this race and I don't see anything missing in > Andrew's tree. I'll go over the code again and re-check but so far I > don't see how this race could occur. Isn't the below race possible? CPU A CPU B exiting: mmap_write_lock remove_vma() mmap_write_unlock process_mrelease: mmap_read_lock __oom_reap_task_mm mmap_read_unlock > > > > > > The below untested patch (compiled) may be able to fix it. > > > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > > index 832fb330376e..c389995bcc71 100644 > > > --- a/mm/oom_kill.c > > > +++ b/mm/oom_kill.c > > > @@ -1185,9 +1185,11 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > > > unsigned int, flags) > > > if (!reap) > > > goto drop_mm; > > > > > > + if (!mmget_not_zero(mm)) > > > + goto drop_mm; > > > if (mmap_read_lock_killable(mm)) { > > > ret = -EINTR; > > > - goto drop_mm; > > > + goto put_mm; > > > } > > > /* > > > * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure > > > @@ -1197,6 +1199,8 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > > > unsigned int, flags) > > > ret = -EAGAIN; > > > mmap_read_unlock(mm); > > > > > > +put_mm: > > > + mmput(mm); > > > drop_mm: > > > mmdrop(mm); > > > put_task: > > > > > > > > > > > The buggy address belongs to the object at ffff88807b868b58 > > > > which belongs to the cache vm_area_struct of size 200 > > > > The buggy address is located 80 bytes inside of > > > > 200-byte region [ffff88807b868b58, ffff88807b868c20) > > > > The buggy address belongs to the page: > > > > page:ffffea0001ee1a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b868 > > > > memcg:ffff88804fe94a01 > > > > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > > > > raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888140006a00 > > > > raw: 0000000000000000 00000000000f000f 00000001ffffffff ffff88804fe94a01 > > > > page dumped because: kasan: bad access detected > > > > page_owner tracks the page as allocated > > > > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 3175, ts 344170603641, free_ts 344164018467 > > > > prep_new_page mm/page_alloc.c:2434 [inline] > > > > get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165 > > > > __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389 > > > > alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271 > > > > alloc_slab_page mm/slub.c:1799 [inline] > > > > allocate_slab mm/slub.c:1944 [inline] > > > > new_slab+0x28a/0x3b0 mm/slub.c:2004 > > > > ___slab_alloc+0x87c/0xe90 mm/slub.c:3018 > > > > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 > > > > slab_alloc_node mm/slub.c:3196 [inline] > > > > slab_alloc mm/slub.c:3238 [inline] > > > > kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3243 > > > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > > > dup_mmap kernel/fork.c:554 [inline] > > > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > > > copy_mm kernel/fork.c:1503 [inline] > > > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > > > __do_sys_clone+0xc8/0x110 kernel/fork.c:2672 > > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > > page last free stack trace: > > > > reset_page_owner include/linux/page_owner.h:24 [inline] > > > > free_pages_prepare mm/page_alloc.c:1352 [inline] > > > > free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404 > > > > free_unref_page_prepare mm/page_alloc.c:3325 [inline] > > > > free_unref_page_list+0x1a9/0xfa0 mm/page_alloc.c:3441 > > > > release_pages+0x317/0x1220 mm/swap.c:980 > > > > tlb_batch_pages_flush mm/mmu_gather.c:50 [inline] > > > > tlb_flush_mmu_free mm/mmu_gather.c:243 [inline] > > > > tlb_flush_mmu mm/mmu_gather.c:250 [inline] > > > > tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:341 > > > > exit_mmap+0x21b/0x670 mm/mmap.c:3180 > > > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > > > mmput+0x56/0x60 kernel/fork.c:1135 > > > > exit_mm kernel/exit.c:507 [inline] > > > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > > > handle_signal_work kernel/entry/common.c:148 [inline] > > > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > > > Memory state around the buggy address: > > > > ffff88807b868a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > > ffff88807b868b00: fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb > > > > >ffff88807b868b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > > ^ > > > > ffff88807b868c00: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb > > > > ffff88807b868c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > > ================================================================== > > > > ---------------- > > > > Code disassembly (best guess): > > > > 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi > > > > 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d > > > > a: 10 06 adc %al,(%rsi) > > > > c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi > > > > 10: 10 07 adc %al,(%rdi) > > > > 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi > > > > 16: 10 08 adc %cl,(%rax) > > > > 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi > > > > 1c: 00 00 add %al,(%rax) > > > > 1e: 00 00 add %al,(%rax) > > > > 20: 00 51 52 add %dl,0x52(%rcx) > > > > 23: 55 push %rbp > > > > 24: 89 e5 mov %esp,%ebp > > > > 26: 0f 34 sysenter > > > > 28: cd 80 int $0x80 > > > > * 2a: 5d pop %rbp <-- trapping instruction > > > > 2b: 5a pop %rdx > > > > 2c: 59 pop %rcx > > > > 2d: c3 retq > > > > 2e: 90 nop > > > > 2f: 90 nop > > > > 30: 90 nop > > > > 31: 90 nop > > > > 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > > 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > > > > > > > > > > --- > > > > This report is generated by a bot. It may contain errors. > > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > > > syzbot will keep track of this issue. See: > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > > > > > -- > > Michal Hocko > > SUSE Labs ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-15 17:53 ` Yang Shi @ 2022-02-15 18:10 ` Suren Baghdasaryan 2022-02-15 19:36 ` Michal Hocko 0 siblings, 1 reply; 9+ messages in thread From: Suren Baghdasaryan @ 2022-02-15 18:10 UTC (permalink / raw) To: Yang Shi Cc: Michal Hocko, syzbot, Andrew Morton, Christian Brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs On Tue, Feb 15, 2022 at 9:53 AM Yang Shi <shy828301@gmail.com> wrote: > > On Tue, Feb 15, 2022 at 9:34 AM Suren Baghdasaryan <surenb@google.com> wrote: > > > > -> > > On Tue, Feb 15, 2022 at 1:59 AM Michal Hocko <mhocko@suse.com> wrote: > > > > > > [Add Suren - and keeping the full message for reference. My comment in > > > inlined] > > > > > > On Mon 14-02-22 11:07:05, Yang Shi wrote: > > > > On Mon, Feb 14, 2022 at 2:44 AM syzbot > > > > <syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com> wrote: > > > > > > > > > > Hello, > > > > > > > > > > syzbot found the following issue on: > > > > > > > > > > HEAD commit: e6251ab4551f Merge tag 'nfs-for-5.17-2' of git://git.linux.. > > > > > git tree: upstream > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1229b2f8700000 > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45 > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=2ccf63a4bd07cf39cab0 > > > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > > userspace arch: i386 > > > > > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > > Reported-by: syzbot+2ccf63a4bd07cf39cab0@syzkaller.appspotmail.com > > > > > > > > > > ================================================================== > > > > > BUG: KASAN: use-after-free in can_madv_lru_vma mm/internal.h:76 [inline] > > > > > BUG: KASAN: use-after-free in __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > > > > Read of size 8 at addr ffff88807b868ba8 by task syz-executor.2/12778 > > > > > > > > > > CPU: 0 PID: 12778 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00029-ge6251ab4551f #0 > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > > > > Call Trace: > > > > > <TASK> > > > > > __dump_stack lib/dump_stack.c:88 [inline] > > > > > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > > > > > print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255 > > > > > __kasan_report mm/kasan/report.c:442 [inline] > > > > > kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 > > > > > can_madv_lru_vma mm/internal.h:76 [inline] > > > > > __oom_reap_task_mm+0x3a4/0x400 mm/oom_kill.c:529 > > > > > __do_sys_process_mrelease+0x3f2/0x450 mm/oom_kill.c:1196 > > > > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > > > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > RIP: 0023:0xf6e70549 > > > > > Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > > > > > RSP: 002b:00000000f586a5cc EFLAGS: 00000296 ORIG_RAX: 00000000000001c0 > > > > > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000 > > > > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > > > > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > > > > > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > > > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > > > > </TASK> > > > > > > > > > > Allocated by task 12778: > > > > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > > > > kasan_set_track mm/kasan/common.c:45 [inline] > > > > > set_alloc_info mm/kasan/common.c:436 [inline] > > > > > __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469 > > > > > kasan_slab_alloc include/linux/kasan.h:260 [inline] > > > > > slab_post_alloc_hook mm/slab.h:732 [inline] > > > > > slab_alloc_node mm/slub.c:3230 [inline] > > > > > slab_alloc mm/slub.c:3238 [inline] > > > > > kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243 > > > > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > > > > dup_mmap kernel/fork.c:554 [inline] > > > > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > > > > copy_mm kernel/fork.c:1503 [inline] > > > > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > > > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > > > > __do_compat_sys_ia32_clone+0xac/0xe0 arch/x86/kernel/sys_ia32.c:254 > > > > > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > > > > > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > > > > > Freed by task 12780: > > > > > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > > > > > kasan_set_track+0x21/0x30 mm/kasan/common.c:45 > > > > > kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 > > > > > ____kasan_slab_free mm/kasan/common.c:366 [inline] > > > > > ____kasan_slab_free+0x130/0x160 mm/kasan/common.c:328 > > > > > kasan_slab_free include/linux/kasan.h:236 [inline] > > > > > slab_free_hook mm/slub.c:1728 [inline] > > > > > slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1754 > > > > > slab_free mm/slub.c:3509 [inline] > > > > > kmem_cache_free+0xd8/0x340 mm/slub.c:3526 > > > > > remove_vma+0x135/0x170 mm/mmap.c:189 > > > > > exit_mmap+0x29a/0x670 mm/mmap.c:3186 > > > > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > > > > mmput+0x56/0x60 kernel/fork.c:1135 > > > > > exit_mm kernel/exit.c:507 [inline] > > > > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > > > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > > > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > > > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > > > > handle_signal_work kernel/entry/common.c:148 [inline] > > > > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > > > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > > > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > > > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > > > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > > > It seems process_mrelease() may be racy with exiting. mmgrab() just > > > > pin mm struct, but doesn't guarantee the associated address space > > > > still exists. mmget or mmget_not_zero() may be needed at first glance. > > > > > > This is what process_mrelease used to do before ba535c1caf3e > > > ("mm/oom_kill: allow process_mrelease to run under mmap_lock > > > protection"). It shouldn't be really necessary because of the > > > synchronization that happens on the exit_mmap level. There were some > > > patches in that area and I am not sure whether something is still > > > hanging in the Andrew's queue. Suren will surely know better. > > > > Correct, the proposed change is what we were doing before 64591e8605d6 > > ("mm: protect free_pgtables with mmap_lock write lock in exit_mmap") > > and ba535c1caf3e ("mm/oom_kill: allow process_mrelease to run under > > mmap_lock protection"). The first patch changed exit_mmap to call > > unlock_range, free_pgtables and remove_vma under mmap_write_lock and > > the second patch calls __oom_reap_task_mm under mmap_read_lock. From > > the call stack IIUC __oom_reap_task_mm at > > https://elixir.bootlin.com/linux/v5.17-rc4/source/mm/oom_kill.c#L1196 > > is racing with remove_vma at > > https://elixir.bootlin.com/linux/v5.17-rc4/source/mm/mmap.c#L3186. The > > mmap_lock should prevent this race and I don't see anything missing in > > Andrew's tree. I'll go over the code again and re-check but so far I > > don't see how this race could occur. > > Isn't the below race possible? > > CPU A CPU B > exiting: > mmap_write_lock > remove_vma() > mmap_write_unlock > process_mrelease: > mmap_read_lock > __oom_reap_task_mm > mmap_read_unlock > Sure, that sequence (would not call it a race) is possible but in this case __oom_reap_task_mm will find no vmas in the mm because exit_mmap freed and removed all of them. > > > > > > > > > The below untested patch (compiled) may be able to fix it. > > > > > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > > > index 832fb330376e..c389995bcc71 100644 > > > > --- a/mm/oom_kill.c > > > > +++ b/mm/oom_kill.c > > > > @@ -1185,9 +1185,11 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > > > > unsigned int, flags) > > > > if (!reap) > > > > goto drop_mm; > > > > > > > > + if (!mmget_not_zero(mm)) > > > > + goto drop_mm; > > > > if (mmap_read_lock_killable(mm)) { > > > > ret = -EINTR; > > > > - goto drop_mm; > > > > + goto put_mm; > > > > } > > > > /* > > > > * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure > > > > @@ -1197,6 +1199,8 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, > > > > unsigned int, flags) > > > > ret = -EAGAIN; > > > > mmap_read_unlock(mm); > > > > > > > > +put_mm: > > > > + mmput(mm); > > > > drop_mm: > > > > mmdrop(mm); > > > > put_task: > > > > > > > > > > > > > > The buggy address belongs to the object at ffff88807b868b58 > > > > > which belongs to the cache vm_area_struct of size 200 > > > > > The buggy address is located 80 bytes inside of > > > > > 200-byte region [ffff88807b868b58, ffff88807b868c20) > > > > > The buggy address belongs to the page: > > > > > page:ffffea0001ee1a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b868 > > > > > memcg:ffff88804fe94a01 > > > > > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > > > > > raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888140006a00 > > > > > raw: 0000000000000000 00000000000f000f 00000001ffffffff ffff88804fe94a01 > > > > > page dumped because: kasan: bad access detected > > > > > page_owner tracks the page as allocated > > > > > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 3175, ts 344170603641, free_ts 344164018467 > > > > > prep_new_page mm/page_alloc.c:2434 [inline] > > > > > get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165 > > > > > __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389 > > > > > alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271 > > > > > alloc_slab_page mm/slub.c:1799 [inline] > > > > > allocate_slab mm/slub.c:1944 [inline] > > > > > new_slab+0x28a/0x3b0 mm/slub.c:2004 > > > > > ___slab_alloc+0x87c/0xe90 mm/slub.c:3018 > > > > > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 > > > > > slab_alloc_node mm/slub.c:3196 [inline] > > > > > slab_alloc mm/slub.c:3238 [inline] > > > > > kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3243 > > > > > vm_area_dup+0x88/0x2b0 kernel/fork.c:357 > > > > > dup_mmap kernel/fork.c:554 [inline] > > > > > dup_mm+0x5fa/0x13e0 kernel/fork.c:1451 > > > > > copy_mm kernel/fork.c:1503 [inline] > > > > > copy_process+0x71f8/0x7300 kernel/fork.c:2164 > > > > > kernel_clone+0xe7/0xab0 kernel/fork.c:2555 > > > > > __do_sys_clone+0xc8/0x110 kernel/fork.c:2672 > > > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > > > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > > > page last free stack trace: > > > > > reset_page_owner include/linux/page_owner.h:24 [inline] > > > > > free_pages_prepare mm/page_alloc.c:1352 [inline] > > > > > free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404 > > > > > free_unref_page_prepare mm/page_alloc.c:3325 [inline] > > > > > free_unref_page_list+0x1a9/0xfa0 mm/page_alloc.c:3441 > > > > > release_pages+0x317/0x1220 mm/swap.c:980 > > > > > tlb_batch_pages_flush mm/mmu_gather.c:50 [inline] > > > > > tlb_flush_mmu_free mm/mmu_gather.c:243 [inline] > > > > > tlb_flush_mmu mm/mmu_gather.c:250 [inline] > > > > > tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:341 > > > > > exit_mmap+0x21b/0x670 mm/mmap.c:3180 > > > > > __mmput+0x122/0x4b0 kernel/fork.c:1114 > > > > > mmput+0x56/0x60 kernel/fork.c:1135 > > > > > exit_mm kernel/exit.c:507 [inline] > > > > > do_exit+0xa3c/0x2a30 kernel/exit.c:793 > > > > > do_group_exit+0xd2/0x2f0 kernel/exit.c:935 > > > > > get_signal+0x4b0/0x28c0 kernel/signal.c:2862 > > > > > arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 > > > > > handle_signal_work kernel/entry/common.c:148 [inline] > > > > > exit_to_user_mode_loop kernel/entry/common.c:172 [inline] > > > > > exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 > > > > > __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] > > > > > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 > > > > > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > > > > > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > > > > > entry_SYSENTER_compat_after_hwframe+0x4d/0x5c > > > > > > > > > > Memory state around the buggy address: > > > > > ffff88807b868a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > > > ffff88807b868b00: fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb > > > > > >ffff88807b868b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > > > ^ > > > > > ffff88807b868c00: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb > > > > > ffff88807b868c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > > > ================================================================== > > > > > ---------------- > > > > > Code disassembly (best guess): > > > > > 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi > > > > > 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d > > > > > a: 10 06 adc %al,(%rsi) > > > > > c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi > > > > > 10: 10 07 adc %al,(%rdi) > > > > > 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi > > > > > 16: 10 08 adc %cl,(%rax) > > > > > 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi > > > > > 1c: 00 00 add %al,(%rax) > > > > > 1e: 00 00 add %al,(%rax) > > > > > 20: 00 51 52 add %dl,0x52(%rcx) > > > > > 23: 55 push %rbp > > > > > 24: 89 e5 mov %esp,%ebp > > > > > 26: 0f 34 sysenter > > > > > 28: cd 80 int $0x80 > > > > > * 2a: 5d pop %rbp <-- trapping instruction > > > > > 2b: 5a pop %rdx > > > > > 2c: 59 pop %rcx > > > > > 2d: c3 retq > > > > > 2e: 90 nop > > > > > 2f: 90 nop > > > > > 30: 90 nop > > > > > 31: 90 nop > > > > > 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > > > 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > > > > > > > > > > > > > --- > > > > > This report is generated by a bot. It may contain errors. > > > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > > > > > syzbot will keep track of this issue. See: > > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > > > > > > > > -- > > > Michal Hocko > > > SUSE Labs ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-15 18:10 ` Suren Baghdasaryan @ 2022-02-15 19:36 ` Michal Hocko 2022-02-15 19:43 ` Suren Baghdasaryan 0 siblings, 1 reply; 9+ messages in thread From: Michal Hocko @ 2022-02-15 19:36 UTC (permalink / raw) To: Suren Baghdasaryan Cc: Yang Shi, syzbot, Andrew Morton, Christian Brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs On Tue 15-02-22 10:10:53, Suren Baghdasaryan wrote: > On Tue, Feb 15, 2022 at 9:53 AM Yang Shi <shy828301@gmail.com> wrote: [...] > > Isn't the below race possible? > > > > CPU A CPU B > > exiting: > > mmap_write_lock > > remove_vma() > > mmap_write_unlock > > process_mrelease: > > mmap_read_lock > > __oom_reap_task_mm > > mmap_read_unlock > > > > Sure, that sequence (would not call it a race) is possible but in this > case __oom_reap_task_mm will find no vmas in the mm because exit_mmap > freed and removed all of them. I didn't really have chance to have a closer look but I do not see exit_mmap doing mm->mmap = NULL so the pointer can be a freed vma unless I am missing something. I thought we've had it in your patches? Has this got lost somewhere in the process? -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-15 19:36 ` Michal Hocko @ 2022-02-15 19:43 ` Suren Baghdasaryan 2022-02-15 20:30 ` Suren Baghdasaryan 0 siblings, 1 reply; 9+ messages in thread From: Suren Baghdasaryan @ 2022-02-15 19:43 UTC (permalink / raw) To: Michal Hocko Cc: Yang Shi, syzbot, Andrew Morton, Christian Brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs On Tue, Feb 15, 2022 at 11:36 AM Michal Hocko <mhocko@suse.com> wrote: > > On Tue 15-02-22 10:10:53, Suren Baghdasaryan wrote: > > On Tue, Feb 15, 2022 at 9:53 AM Yang Shi <shy828301@gmail.com> wrote: > [...] > > > Isn't the below race possible? > > > > > > CPU A CPU B > > > exiting: > > > mmap_write_lock > > > remove_vma() > > > mmap_write_unlock > > > process_mrelease: > > > mmap_read_lock > > > __oom_reap_task_mm > > > mmap_read_unlock > > > > > > > Sure, that sequence (would not call it a race) is possible but in this > > case __oom_reap_task_mm will find no vmas in the mm because exit_mmap > > freed and removed all of them. > > I didn't really have chance to have a closer look but I do not see > exit_mmap doing mm->mmap = NULL so the pointer can be a freed vma unless > I am missing something. I thought we've had it in your patches? Has this > got lost somewhere in the process? Doh! Yes, it looks like I completely missed the actual pointer. That must be it since I don't see any other possibility. Will post a patch shortly. Thanks! > -- > Michal Hocko > SUSE Labs ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm 2022-02-15 19:43 ` Suren Baghdasaryan @ 2022-02-15 20:30 ` Suren Baghdasaryan 0 siblings, 0 replies; 9+ messages in thread From: Suren Baghdasaryan @ 2022-02-15 20:30 UTC (permalink / raw) To: Michal Hocko Cc: Yang Shi, syzbot, Andrew Morton, Christian Brauner, Linux Kernel Mailing List, Linux MM, syzkaller-bugs On Tue, Feb 15, 2022 at 11:43 AM Suren Baghdasaryan <surenb@google.com> wrote: > > On Tue, Feb 15, 2022 at 11:36 AM Michal Hocko <mhocko@suse.com> wrote: > > > > On Tue 15-02-22 10:10:53, Suren Baghdasaryan wrote: > > > On Tue, Feb 15, 2022 at 9:53 AM Yang Shi <shy828301@gmail.com> wrote: > > [...] > > > > Isn't the below race possible? > > > > > > > > CPU A CPU B > > > > exiting: > > > > mmap_write_lock > > > > remove_vma() > > > > mmap_write_unlock > > > > process_mrelease: > > > > mmap_read_lock > > > > __oom_reap_task_mm > > > > mmap_read_unlock > > > > > > > > > > Sure, that sequence (would not call it a race) is possible but in this > > > case __oom_reap_task_mm will find no vmas in the mm because exit_mmap > > > freed and removed all of them. > > > > I didn't really have chance to have a closer look but I do not see > > exit_mmap doing mm->mmap = NULL so the pointer can be a freed vma unless > > I am missing something. I thought we've had it in your patches? Has this > > got lost somewhere in the process? > > Doh! Yes, it looks like I completely missed the actual pointer. That > must be it since I don't see any other possibility. Will post a patch > shortly. Fix posted at https://lore.kernel.org/all/20220215201922.1908156-1-surenb@google.com/ > Thanks! > > > -- > > Michal Hocko > > SUSE Labs ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2022-02-15 20:30 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-02-14 10:44 [syzbot] KASAN: use-after-free Read in __oom_reap_task_mm syzbot 2022-02-14 19:07 ` Yang Shi 2022-02-15 9:59 ` Michal Hocko 2022-02-15 17:34 ` Suren Baghdasaryan 2022-02-15 17:53 ` Yang Shi 2022-02-15 18:10 ` Suren Baghdasaryan 2022-02-15 19:36 ` Michal Hocko 2022-02-15 19:43 ` Suren Baghdasaryan 2022-02-15 20:30 ` Suren Baghdasaryan
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