* KASAN: use-after-free Read in rtnetlink_put_metrics
@ 2018-07-31 12:31 syzbot
2018-07-31 12:41 ` Eric Dumazet
0 siblings, 1 reply; 10+ messages in thread
From: syzbot @ 2018-07-31 12:31 UTC (permalink / raw)
To: christian.brauner, davem, dsahern, fw, jbenc, ktkhai,
linux-kernel, lucien.xin, netdev, syzkaller-bugs
Hello,
syzbot found the following crash on:
HEAD commit: 61f4b23769f0 netlink: Don't shift with UB on nlk->ngroups
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=14a9de58400000
kernel config: https://syzkaller.appspot.com/x/.config?x=ffb4428fdc82f93b
dashboard link: https://syzkaller.appspot.com/bug?extid=41f9c04b50ef70c66947
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
Unfortunately, I don't have any reproducer for this crash yet.
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+41f9c04b50ef70c66947@syzkaller.appspotmail.com
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending
cookies. Check SNMP counters.
==================================================================
BUG: KASAN: use-after-free in rtnetlink_put_metrics+0x621/0x690
net/core/rtnetlink.c:754
Read of size 4 at addr ffff8801b3cd8b00 by task udevd/2613
CPU: 0 PID: 2613 Comm: udevd Not tainted 4.18.0-rc6+ #34
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
rtnetlink_put_metrics+0x621/0x690 net/core/rtnetlink.c:754
rt6_fill_node+0x7d9/0x1540 net/ipv6/route.c:4753
inet6_rt_notify+0x161/0x2c0 net/ipv6/route.c:4985
fib6_del_route net/ipv6/ip6_fib.c:1788 [inline]
fib6_del+0xf4d/0x1310 net/ipv6/ip6_fib.c:1815
fib6_clean_node+0x3ee/0x5e0 net/ipv6/ip6_fib.c:1976
fib6_walk_continue+0x4b1/0x8e0 net/ipv6/ip6_fib.c:1899
fib6_walk+0x95/0xf0 net/ipv6/ip6_fib.c:1947
fib6_clean_tree+0x1ea/0x360 net/ipv6/ip6_fib.c:2024
__fib6_clean_all+0x21c/0x420 net/ipv6/ip6_fib.c:2040
fib6_clean_all net/ipv6/ip6_fib.c:2051 [inline]
fib6_run_gc+0x182/0x3d0 net/ipv6/ip6_fib.c:2107
fib6_gc_timer_cb+0x20/0x30 net/ipv6/ip6_fib.c:2124
call_timer_fn+0x242/0x970 kernel/time/timer.c:1326
expire_timers kernel/time/timer.c:1363 [inline]
__run_timers+0x7a6/0xc70 kernel/time/timer.c:1666
run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
__do_softirq+0x2e8/0xb17 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x1d4/0x210 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:527 [inline]
smp_apic_timer_interrupt+0x186/0x730 arch/x86/kernel/apic/apic.c:1052
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783
[inline]
RIP: 0010:qlink_free mm/kasan/quarantine.c:150 [inline]
RIP: 0010:qlist_free_all+0xf8/0x160 mm/kasan/quarantine.c:166
Code: c7 40 10 00 00 00 00 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8
57 b8 a4 ff 48 83 3d 67 b4 37 06 00 74 56 48 89 df 57 9d <0f> 1f 44 00 00
eb af ba 00 00 00 80 48 01 c2 72 43 48 b9 00 00 00
RSP: 0018:ffff8801b54a7b08 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: 0000000000000286 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8801b5498a38 RDI: 0000000000000286
RBP: ffff8801b54a7b40 R08: ffff8801b5498a38 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8801dad85dc0 R14: ffff8801b37ace00 R15: ffffffff87f1b0a0
quarantine_reduce+0x163/0x1a0 mm/kasan/quarantine.c:259
kasan_kmalloc+0x99/0xe0 mm/kasan/kasan.c:538
kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
slab_post_alloc_hook mm/slab.h:444 [inline]
slab_alloc mm/slab.c:3392 [inline]
kmem_cache_alloc+0x11b/0x760 mm/slab.c:3552
getname_flags+0xd0/0x5a0 fs/namei.c:140
user_path_at_empty+0x2d/0x50 fs/namei.c:2584
do_readlinkat+0x14b/0x400 fs/stat.c:394
__do_sys_readlink fs/stat.c:427 [inline]
__se_sys_readlink fs/stat.c:424 [inline]
__x64_sys_readlink+0x78/0xb0 fs/stat.c:424
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7efd8271b577
Code: f0 ff ff 77 02 f3 c3 48 8b 15 bd 38 2b 00 f7 d8 64 89 02 83 c8 ff c3
90 90 90 90 90 90 90 90 90 90 90 90 b8 59 00 00 00 0f 05 <48> 3d 01 f0 ff
ff 73 01 c3 48 8b 0d 91 38 2b 00 31 d2 48 29 c2 64
RSP: 002b:00007ffe27d23688 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00000000021de250 RCX: 00007efd8271b577
RDX: 0000000000000400 RSI: 00007ffe27d23690 RDI: 00007ffe27d23b70
RBP: 00007ffe27d243b0 R08: 00007ffe27d243b0 R09: 00007efd8276fdc0
R10: 7665642f7379732f R11: 0000000000000246 R12: 00007ffe27d23b70
R13: 0000000000000400 R14: 00000000021de250 R15: 00000000021e3e10
Allocated by task 8953:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
kmalloc include/linux/slab.h:513 [inline]
kzalloc include/linux/slab.h:707 [inline]
fib6_metric_set+0x163/0x2c0 net/ipv6/ip6_fib.c:645
fib6_add_rt2node+0xe36/0x27f0 net/ipv6/ip6_fib.c:1000
fib6_add+0xaae/0x14d0 net/ipv6/ip6_fib.c:1308
__ip6_ins_rt+0x54/0x80 net/ipv6/route.c:1163
ip6_route_add+0x6d/0xc0 net/ipv6/route.c:3171
addrconf_prefix_route.isra.48+0x51d/0x720 net/ipv6/addrconf.c:2347
inet6_addr_modify net/ipv6/addrconf.c:4627 [inline]
inet6_rtm_newaddr+0x112e/0x1b50 net/ipv6/addrconf.c:4743
rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4665
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2453
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4683
netlink_unicast_kernel net/netlink/af_netlink.c:1315 [inline]
netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1341
netlink_sendmsg+0xa18/0xfd0 net/netlink/af_netlink.c:1906
sock_sendmsg_nosec net/socket.c:642 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:652
___sys_sendmsg+0x7fd/0x930 net/socket.c:2126
__sys_sendmsg+0x11d/0x290 net/socket.c:2164
__do_sys_sendmsg net/socket.c:2173 [inline]
__se_sys_sendmsg net/socket.c:2171 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2171
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 2613:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xd9/0x260 mm/slab.c:3813
fib6_metrics_release+0x77/0x90 net/ipv6/ip6_fib.c:179
fib6_drop_pcpu_from net/ipv6/ip6_fib.c:899 [inline]
fib6_purge_rt+0x5ec/0x7f0 net/ipv6/ip6_fib.c:934
fib6_del_route net/ipv6/ip6_fib.c:1784 [inline]
fib6_del+0xc11/0x1310 net/ipv6/ip6_fib.c:1815
fib6_clean_node+0x3ee/0x5e0 net/ipv6/ip6_fib.c:1976
fib6_walk_continue+0x4b1/0x8e0 net/ipv6/ip6_fib.c:1899
fib6_walk+0x95/0xf0 net/ipv6/ip6_fib.c:1947
fib6_clean_tree+0x1ea/0x360 net/ipv6/ip6_fib.c:2024
__fib6_clean_all+0x21c/0x420 net/ipv6/ip6_fib.c:2040
fib6_clean_all net/ipv6/ip6_fib.c:2051 [inline]
fib6_run_gc+0x182/0x3d0 net/ipv6/ip6_fib.c:2107
fib6_gc_timer_cb+0x20/0x30 net/ipv6/ip6_fib.c:2124
call_timer_fn+0x242/0x970 kernel/time/timer.c:1326
expire_timers kernel/time/timer.c:1363 [inline]
__run_timers+0x7a6/0xc70 kernel/time/timer.c:1666
run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
__do_softirq+0x2e8/0xb17 kernel/softirq.c:292
The buggy address belongs to the object at ffff8801b3cd8b00
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes inside of
96-byte region [ffff8801b3cd8b00, ffff8801b3cd8b60)
The buggy address belongs to the page:
page:ffffea0006cf3600 count:1 mapcount:0 mapping:ffff8801dac004c0 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0006a6f3c8 ffffea0007018608 ffff8801dac004c0
raw: 0000000000000000 ffff8801b3cd8000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8801b3cd8a00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8801b3cd8a80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> ffff8801b3cd8b00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff8801b3cd8b80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8801b3cd8c00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================
---
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-07-31 12:31 KASAN: use-after-free Read in rtnetlink_put_metrics syzbot @ 2018-07-31 12:41 ` Eric Dumazet 2018-07-31 13:40 ` Sabrina Dubroca 0 siblings, 1 reply; 10+ messages in thread From: Eric Dumazet @ 2018-07-31 12:41 UTC (permalink / raw) To: syzbot, christian.brauner, davem, dsahern, fw, jbenc, ktkhai, linux-kernel, lucien.xin, netdev, syzkaller-bugs, Sabrina Dubroca On 07/31/2018 05:31 AM, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 61f4b23769f0 netlink: Don't shift with UB on nlk->ngroups > git tree: net > console output: https://syzkaller.appspot.com/x/log.txt?x=14a9de58400000 > kernel config: https://syzkaller.appspot.com/x/.config?x=ffb4428fdc82f93b > dashboard link: https://syzkaller.appspot.com/bug?extid=41f9c04b50ef70c66947 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+41f9c04b50ef70c66947@syzkaller.appspotmail.com > > TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. > ================================================================== > BUG: KASAN: use-after-free in rtnetlink_put_metrics+0x621/0x690 net/core/rtnetlink.c:754 > Read of size 4 at addr ffff8801b3cd8b00 by task udevd/2613 > > CPU: 0 PID: 2613 Comm: udevd Not tainted 4.18.0-rc6+ #34 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > <IRQ> > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113 > print_address_description+0x6c/0x20b mm/kasan/report.c:256 > kasan_report_error mm/kasan/report.c:354 [inline] > kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 > __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432 > rtnetlink_put_metrics+0x621/0x690 net/core/rtnetlink.c:754 > rt6_fill_node+0x7d9/0x1540 net/ipv6/route.c:4753 > inet6_rt_notify+0x161/0x2c0 net/ipv6/route.c:4985 > fib6_del_route net/ipv6/ip6_fib.c:1788 [inline] > fib6_del+0xf4d/0x1310 net/ipv6/ip6_fib.c:1815 > fib6_clean_node+0x3ee/0x5e0 net/ipv6/ip6_fib.c:1976 > fib6_walk_continue+0x4b1/0x8e0 net/ipv6/ip6_fib.c:1899 > fib6_walk+0x95/0xf0 net/ipv6/ip6_fib.c:1947 > fib6_clean_tree+0x1ea/0x360 net/ipv6/ip6_fib.c:2024 > __fib6_clean_all+0x21c/0x420 net/ipv6/ip6_fib.c:2040 > fib6_clean_all net/ipv6/ip6_fib.c:2051 [inline] > fib6_run_gc+0x182/0x3d0 net/ipv6/ip6_fib.c:2107 > fib6_gc_timer_cb+0x20/0x30 net/ipv6/ip6_fib.c:2124 > call_timer_fn+0x242/0x970 kernel/time/timer.c:1326 > expire_timers kernel/time/timer.c:1363 [inline] > __run_timers+0x7a6/0xc70 kernel/time/timer.c:1666 > run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692 > __do_softirq+0x2e8/0xb17 kernel/softirq.c:292 > invoke_softirq kernel/softirq.c:372 [inline] > irq_exit+0x1d4/0x210 kernel/softirq.c:412 > exiting_irq arch/x86/include/asm/apic.h:527 [inline] > smp_apic_timer_interrupt+0x186/0x730 arch/x86/kernel/apic/apic.c:1052 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863 > </IRQ> > RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783 [inline] > RIP: 0010:qlink_free mm/kasan/quarantine.c:150 [inline] > RIP: 0010:qlist_free_all+0xf8/0x160 mm/kasan/quarantine.c:166 > Code: c7 40 10 00 00 00 00 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 57 b8 a4 ff 48 83 3d 67 b4 37 06 00 74 56 48 89 df 57 9d <0f> 1f 44 00 00 eb af ba 00 00 00 80 48 01 c2 72 43 48 b9 00 00 00 > RSP: 0018:ffff8801b54a7b08 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 > RAX: 0000000000000007 RBX: 0000000000000286 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: ffff8801b5498a38 RDI: 0000000000000286 > RBP: ffff8801b54a7b40 R08: ffff8801b5498a38 R09: 0000000000000006 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: ffff8801dad85dc0 R14: ffff8801b37ace00 R15: ffffffff87f1b0a0 > quarantine_reduce+0x163/0x1a0 mm/kasan/quarantine.c:259 > kasan_kmalloc+0x99/0xe0 mm/kasan/kasan.c:538 > kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 > slab_post_alloc_hook mm/slab.h:444 [inline] > slab_alloc mm/slab.c:3392 [inline] > kmem_cache_alloc+0x11b/0x760 mm/slab.c:3552 > getname_flags+0xd0/0x5a0 fs/namei.c:140 > user_path_at_empty+0x2d/0x50 fs/namei.c:2584 > do_readlinkat+0x14b/0x400 fs/stat.c:394 > __do_sys_readlink fs/stat.c:427 [inline] > __se_sys_readlink fs/stat.c:424 [inline] > __x64_sys_readlink+0x78/0xb0 fs/stat.c:424 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x7efd8271b577 > Code: f0 ff ff 77 02 f3 c3 48 8b 15 bd 38 2b 00 f7 d8 64 89 02 83 c8 ff c3 90 90 90 90 90 90 90 90 90 90 90 90 b8 59 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 91 38 2b 00 31 d2 48 29 c2 64 > RSP: 002b:00007ffe27d23688 EFLAGS: 00000246 ORIG_RAX: 0000000000000059 > RAX: ffffffffffffffda RBX: 00000000021de250 RCX: 00007efd8271b577 > RDX: 0000000000000400 RSI: 00007ffe27d23690 RDI: 00007ffe27d23b70 > RBP: 00007ffe27d243b0 R08: 00007ffe27d243b0 R09: 00007efd8276fdc0 > R10: 7665642f7379732f R11: 0000000000000246 R12: 00007ffe27d23b70 > R13: 0000000000000400 R14: 00000000021de250 R15: 00000000021e3e10 > > Allocated by task 8953: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 > kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620 > kmalloc include/linux/slab.h:513 [inline] > kzalloc include/linux/slab.h:707 [inline] > fib6_metric_set+0x163/0x2c0 net/ipv6/ip6_fib.c:645 > fib6_add_rt2node+0xe36/0x27f0 net/ipv6/ip6_fib.c:1000 > fib6_add+0xaae/0x14d0 net/ipv6/ip6_fib.c:1308 > __ip6_ins_rt+0x54/0x80 net/ipv6/route.c:1163 > ip6_route_add+0x6d/0xc0 net/ipv6/route.c:3171 > addrconf_prefix_route.isra.48+0x51d/0x720 net/ipv6/addrconf.c:2347 > inet6_addr_modify net/ipv6/addrconf.c:4627 [inline] > inet6_rtm_newaddr+0x112e/0x1b50 net/ipv6/addrconf.c:4743 > rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4665 > netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2453 > rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4683 > netlink_unicast_kernel net/netlink/af_netlink.c:1315 [inline] > netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1341 > netlink_sendmsg+0xa18/0xfd0 net/netlink/af_netlink.c:1906 > sock_sendmsg_nosec net/socket.c:642 [inline] > sock_sendmsg+0xd5/0x120 net/socket.c:652 > ___sys_sendmsg+0x7fd/0x930 net/socket.c:2126 > __sys_sendmsg+0x11d/0x290 net/socket.c:2164 > __do_sys_sendmsg net/socket.c:2173 [inline] > __se_sys_sendmsg net/socket.c:2171 [inline] > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2171 > do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 2613: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 > kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 > __cache_free mm/slab.c:3498 [inline] > kfree+0xd9/0x260 mm/slab.c:3813 > fib6_metrics_release+0x77/0x90 net/ipv6/ip6_fib.c:179 > fib6_drop_pcpu_from net/ipv6/ip6_fib.c:899 [inline] > fib6_purge_rt+0x5ec/0x7f0 net/ipv6/ip6_fib.c:934 > fib6_del_route net/ipv6/ip6_fib.c:1784 [inline] > fib6_del+0xc11/0x1310 net/ipv6/ip6_fib.c:1815 > fib6_clean_node+0x3ee/0x5e0 net/ipv6/ip6_fib.c:1976 > fib6_walk_continue+0x4b1/0x8e0 net/ipv6/ip6_fib.c:1899 > fib6_walk+0x95/0xf0 net/ipv6/ip6_fib.c:1947 > fib6_clean_tree+0x1ea/0x360 net/ipv6/ip6_fib.c:2024 > __fib6_clean_all+0x21c/0x420 net/ipv6/ip6_fib.c:2040 > fib6_clean_all net/ipv6/ip6_fib.c:2051 [inline] > fib6_run_gc+0x182/0x3d0 net/ipv6/ip6_fib.c:2107 > fib6_gc_timer_cb+0x20/0x30 net/ipv6/ip6_fib.c:2124 > call_timer_fn+0x242/0x970 kernel/time/timer.c:1326 > expire_timers kernel/time/timer.c:1363 [inline] > __run_timers+0x7a6/0xc70 kernel/time/timer.c:1666 > run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692 > __do_softirq+0x2e8/0xb17 kernel/softirq.c:292 > > The buggy address belongs to the object at ffff8801b3cd8b00 > which belongs to the cache kmalloc-96 of size 96 > The buggy address is located 0 bytes inside of > 96-byte region [ffff8801b3cd8b00, ffff8801b3cd8b60) > The buggy address belongs to the page: > page:ffffea0006cf3600 count:1 mapcount:0 mapping:ffff8801dac004c0 index:0x0 > flags: 0x2fffc0000000100(slab) > raw: 02fffc0000000100 ffffea0006a6f3c8 ffffea0007018608 ffff8801dac004c0 > raw: 0000000000000000 ffff8801b3cd8000 0000000100000020 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801b3cd8a00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ffff8801b3cd8a80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >> ffff8801b3cd8b00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ^ > ffff8801b3cd8b80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ffff8801b3cd8c00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ================================================================== > > > --- > This bug 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 bug report. See: > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot. Probably also caused by : commit df18b50448fab1dff093731dfd0e25e77e1afcd1 Author: Sabrina Dubroca <sd@queasysnail.net> Date: Mon Jul 30 16:23:10 2018 +0200 net/ipv6: fix metrics leak ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-07-31 12:41 ` Eric Dumazet @ 2018-07-31 13:40 ` Sabrina Dubroca 2018-07-31 21:53 ` David Miller 2018-07-31 23:03 ` Cong Wang 0 siblings, 2 replies; 10+ messages in thread From: Sabrina Dubroca @ 2018-07-31 13:40 UTC (permalink / raw) To: Eric Dumazet Cc: syzbot, christian.brauner, davem, dsahern, fw, jbenc, ktkhai, linux-kernel, lucien.xin, netdev, syzkaller-bugs 2018-07-31, 05:41:56 -0700, Eric Dumazet wrote: > > > On 07/31/2018 05:31 AM, syzbot wrote: > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 61f4b23769f0 netlink: Don't shift with UB on nlk->ngroups > > git tree: net > > console output: https://syzkaller.appspot.com/x/log.txt?x=14a9de58400000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=ffb4428fdc82f93b > > dashboard link: https://syzkaller.appspot.com/bug?extid=41f9c04b50ef70c66947 > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > > > Unfortunately, I don't have any reproducer for this crash yet. [...] > Probably also caused by : > > > commit df18b50448fab1dff093731dfd0e25e77e1afcd1 > Author: Sabrina Dubroca <sd@queasysnail.net> > Date: Mon Jul 30 16:23:10 2018 +0200 > > net/ipv6: fix metrics leak Yeah, I'm looking into both those reports :/ -- Sabrina ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-07-31 13:40 ` Sabrina Dubroca @ 2018-07-31 21:53 ` David Miller 2018-07-31 23:03 ` Cong Wang 1 sibling, 0 replies; 10+ messages in thread From: David Miller @ 2018-07-31 21:53 UTC (permalink / raw) To: sd Cc: eric.dumazet, syzbot+41f9c04b50ef70c66947, christian.brauner, dsahern, fw, jbenc, ktkhai, linux-kernel, lucien.xin, netdev, syzkaller-bugs From: Sabrina Dubroca <sd@queasysnail.net> Date: Tue, 31 Jul 2018 15:40:14 +0200 > 2018-07-31, 05:41:56 -0700, Eric Dumazet wrote: >> Probably also caused by : >> >> >> commit df18b50448fab1dff093731dfd0e25e77e1afcd1 >> Author: Sabrina Dubroca <sd@queasysnail.net> >> Date: Mon Jul 30 16:23:10 2018 +0200 >> >> net/ipv6: fix metrics leak > > Yeah, I'm looking into both those reports :/ Please get me a fix for this soon, because as you can imagine this is going to hold up the 4.18 release. Thanks. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-07-31 13:40 ` Sabrina Dubroca 2018-07-31 21:53 ` David Miller @ 2018-07-31 23:03 ` Cong Wang 2018-08-01 8:15 ` Sabrina Dubroca 2018-08-01 18:46 ` David Miller 1 sibling, 2 replies; 10+ messages in thread From: Cong Wang @ 2018-07-31 23:03 UTC (permalink / raw) To: Sabrina Dubroca Cc: Eric Dumazet, syzbot+41f9c04b50ef70c66947, christian.brauner, David Miller, David Ahern, Florian Westphal, Jiri Benc, Kirill Tkhai, LKML, lucien xin, Linux Kernel Network Developers, syzkaller-bugs On Tue, Jul 31, 2018 at 6:41 AM Sabrina Dubroca <sd@queasysnail.net> wrote: > > 2018-07-31, 05:41:56 -0700, Eric Dumazet wrote: > > > > > > On 07/31/2018 05:31 AM, syzbot wrote: > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: 61f4b23769f0 netlink: Don't shift with UB on nlk->ngroups > > > git tree: net > > > console output: https://syzkaller.appspot.com/x/log.txt?x=14a9de58400000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=ffb4428fdc82f93b > > > dashboard link: https://syzkaller.appspot.com/bug?extid=41f9c04b50ef70c66947 > > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > [...] > > > Probably also caused by : > > > > > > commit df18b50448fab1dff093731dfd0e25e77e1afcd1 > > Author: Sabrina Dubroca <sd@queasysnail.net> > > Date: Mon Jul 30 16:23:10 2018 +0200 > > > > net/ipv6: fix metrics leak > > Yeah, I'm looking into both those reports :/ Looks like this commit is completely unnecessary, fib6_drop_pcpu_from() calls fib6_info_release() which calls fib6_info_destroy_rcu(), so this metrics will be released twice... ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-07-31 23:03 ` Cong Wang @ 2018-08-01 8:15 ` Sabrina Dubroca 2018-08-01 8:28 ` David Ahern 2018-08-02 5:23 ` Cong Wang 2018-08-01 18:46 ` David Miller 1 sibling, 2 replies; 10+ messages in thread From: Sabrina Dubroca @ 2018-08-01 8:15 UTC (permalink / raw) To: Cong Wang Cc: Eric Dumazet, syzbot+41f9c04b50ef70c66947, christian.brauner, David Miller, David Ahern, Florian Westphal, Jiri Benc, Kirill Tkhai, LKML, lucien xin, Linux Kernel Network Developers, syzkaller-bugs 2018-07-31, 16:03:13 -0700, Cong Wang wrote: > On Tue, Jul 31, 2018 at 6:41 AM Sabrina Dubroca <sd@queasysnail.net> wrote: > > > > 2018-07-31, 05:41:56 -0700, Eric Dumazet wrote: > > > > > > > > > On 07/31/2018 05:31 AM, syzbot wrote: > > > > Hello, > > > > > > > > syzbot found the following crash on: > > > > > > > > HEAD commit: 61f4b23769f0 netlink: Don't shift with UB on nlk->ngroups > > > > git tree: net > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=14a9de58400000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=ffb4428fdc82f93b > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=41f9c04b50ef70c66947 > > > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > [...] > > > > > Probably also caused by : > > > > > > > > > commit df18b50448fab1dff093731dfd0e25e77e1afcd1 > > > Author: Sabrina Dubroca <sd@queasysnail.net> > > > Date: Mon Jul 30 16:23:10 2018 +0200 > > > > > > net/ipv6: fix metrics leak > > > > Yeah, I'm looking into both those reports :/ > > Looks like this commit is completely unnecessary, > fib6_drop_pcpu_from() calls fib6_info_release() > which calls fib6_info_destroy_rcu(), so this metrics > will be released twice... kmemleak disagrees: unreferenced object 0xffff88006b605080 (size 96): comm "ip", pid 433, jiffies 4294889793 (age 74.844s) hex dump (first 32 bytes): 00 00 00 00 f4 01 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<000000002650e4e2>] ip6_route_info_create+0x770/0x4050 [<000000000a8d4c52>] ip6_route_add+0x18/0x90 [<00000000474d669c>] inet6_rtm_newroute+0xeb/0x100 [<0000000019fb732d>] rtnetlink_rcv_msg+0x3b5/0xb40 [<000000006f891e19>] netlink_rcv_skb+0x137/0x380 [<0000000070451985>] netlink_unicast+0x47f/0x6e0 [<000000004487d656>] netlink_sendmsg+0x7a7/0x10c0 [<0000000089fdf5ae>] sock_sendmsg+0xac/0x160 [<00000000aae19c54>] ___sys_sendmsg+0x6e0/0xbb0 [<00000000a3906352>] __sys_sendmsg+0xdc/0x230 [<00000000c7c8548a>] do_syscall_64+0x15d/0x740 [<000000007dfdad73>] entry_SYSCALL_64_after_hwframe+0x49/0xbe [<000000003adb705a>] 0xffffffffffffffff ip netns add peerA ip link add eth0 netns peerA type veth peer name ethA ip -net peerA link set eth0 up ip -net peerA link set lo up ip -net peerA a a fec0:A::1/64 dev eth0 ip -net peerA route add fec0:B::/64 via fec0:A:: mtu 1300 ip netns exec peerA nc fec0:B::1 1234 ip -net peerA route del fec0:B::/64 ip netns del peerA -- Sabrina ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-08-01 8:15 ` Sabrina Dubroca @ 2018-08-01 8:28 ` David Ahern 2018-08-02 5:23 ` Cong Wang 1 sibling, 0 replies; 10+ messages in thread From: David Ahern @ 2018-08-01 8:28 UTC (permalink / raw) To: Sabrina Dubroca, Cong Wang Cc: Eric Dumazet, syzbot+41f9c04b50ef70c66947, christian.brauner, David Miller, Florian Westphal, Jiri Benc, Kirill Tkhai, LKML, lucien xin, Linux Kernel Network Developers, syzkaller-bugs On 8/1/18 10:15 AM, Sabrina Dubroca wrote: > ip -net peerA route add fec0:B::/64 via fec0:A:: mtu 1300 I am on vacation right now with limited access to internet, so not able to take a look. In submitting the fib6_info changes I did tests like this and did not see memleak reports (and verified the metrics refcnts with printks), so I am surprised to see your patch in this area. Will take a look when I can but that will not be for a couple more weeks. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-08-01 8:15 ` Sabrina Dubroca 2018-08-01 8:28 ` David Ahern @ 2018-08-02 5:23 ` Cong Wang 1 sibling, 0 replies; 10+ messages in thread From: Cong Wang @ 2018-08-02 5:23 UTC (permalink / raw) To: Sabrina Dubroca Cc: Eric Dumazet, syzbot+41f9c04b50ef70c66947, Christian Brauner, David Miller, David Ahern, Florian Westphal, Jiri Benc, Kirill Tkhai, LKML, lucien xin, Linux Kernel Network Developers, syzkaller-bugs On Wed, Aug 1, 2018 at 1:15 AM Sabrina Dubroca <sd@queasysnail.net> wrote: > > 2018-07-31, 16:03:13 -0700, Cong Wang wrote: > > On Tue, Jul 31, 2018 at 6:41 AM Sabrina Dubroca <sd@queasysnail.net> wrote: > > > > > > 2018-07-31, 05:41:56 -0700, Eric Dumazet wrote: > > > > > > > > > > > > On 07/31/2018 05:31 AM, syzbot wrote: > > > > > Hello, > > > > > > > > > > syzbot found the following crash on: > > > > > > > > > > HEAD commit: 61f4b23769f0 netlink: Don't shift with UB on nlk->ngroups > > > > > git tree: net > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=14a9de58400000 > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=ffb4428fdc82f93b > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=41f9c04b50ef70c66947 > > > > > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > > > > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > [...] > > > > > > > Probably also caused by : > > > > > > > > > > > > commit df18b50448fab1dff093731dfd0e25e77e1afcd1 > > > > Author: Sabrina Dubroca <sd@queasysnail.net> > > > > Date: Mon Jul 30 16:23:10 2018 +0200 > > > > > > > > net/ipv6: fix metrics leak > > > > > > Yeah, I'm looking into both those reports :/ > > > > Looks like this commit is completely unnecessary, > > fib6_drop_pcpu_from() calls fib6_info_release() > > which calls fib6_info_destroy_rcu(), so this metrics > > will be released twice... > > kmemleak disagrees: This information is missing from changelog. :) > > unreferenced object 0xffff88006b605080 (size 96): > comm "ip", pid 433, jiffies 4294889793 (age 74.844s) > hex dump (first 32 bytes): > 00 00 00 00 f4 01 00 00 00 00 00 00 00 00 00 00 ................ > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > backtrace: > [<000000002650e4e2>] ip6_route_info_create+0x770/0x4050 > [<000000000a8d4c52>] ip6_route_add+0x18/0x90 > [<00000000474d669c>] inet6_rtm_newroute+0xeb/0x100 > [<0000000019fb732d>] rtnetlink_rcv_msg+0x3b5/0xb40 > [<000000006f891e19>] netlink_rcv_skb+0x137/0x380 > [<0000000070451985>] netlink_unicast+0x47f/0x6e0 > [<000000004487d656>] netlink_sendmsg+0x7a7/0x10c0 > [<0000000089fdf5ae>] sock_sendmsg+0xac/0x160 > [<00000000aae19c54>] ___sys_sendmsg+0x6e0/0xbb0 > [<00000000a3906352>] __sys_sendmsg+0xdc/0x230 > [<00000000c7c8548a>] do_syscall_64+0x15d/0x740 > [<000000007dfdad73>] entry_SYSCALL_64_after_hwframe+0x49/0xbe > [<000000003adb705a>] 0xffffffffffffffff My kernel dev machine is broken now. I will take a look tomorrow after I fix my kernel dev machine. Thanks! ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-07-31 23:03 ` Cong Wang 2018-08-01 8:15 ` Sabrina Dubroca @ 2018-08-01 18:46 ` David Miller 2018-08-01 19:26 ` Sabrina Dubroca 1 sibling, 1 reply; 10+ messages in thread From: David Miller @ 2018-08-01 18:46 UTC (permalink / raw) To: xiyou.wangcong Cc: sd, eric.dumazet, syzbot+41f9c04b50ef70c66947, christian.brauner, dsahern, fw, jbenc, ktkhai, linux-kernel, lucien.xin, netdev, syzkaller-bugs From: Cong Wang <xiyou.wangcong@gmail.com> Date: Tue, 31 Jul 2018 16:03:13 -0700 > Looks like this commit is completely unnecessary, > fib6_drop_pcpu_from() calls fib6_info_release() > which calls fib6_info_destroy_rcu(), so this metrics > will be released twice... And even if there was a leak here, it's illegal to free this metrics memory synchronously since it is RCU protected. That's why it normally goes through fib6_info_destroy_rcu(). Sabrina, I'm going to revert your changes unless I see some progress here by the end of today. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: KASAN: use-after-free Read in rtnetlink_put_metrics 2018-08-01 18:46 ` David Miller @ 2018-08-01 19:26 ` Sabrina Dubroca 0 siblings, 0 replies; 10+ messages in thread From: Sabrina Dubroca @ 2018-08-01 19:26 UTC (permalink / raw) To: David Miller Cc: xiyou.wangcong, eric.dumazet, syzbot+41f9c04b50ef70c66947, christian.brauner, dsahern, fw, jbenc, ktkhai, linux-kernel, lucien.xin, netdev, syzkaller-bugs 2018-08-01, 11:46:36 -0700, David Miller wrote: > From: Cong Wang <xiyou.wangcong@gmail.com> > Date: Tue, 31 Jul 2018 16:03:13 -0700 > > > Looks like this commit is completely unnecessary, > > fib6_drop_pcpu_from() calls fib6_info_release() > > which calls fib6_info_destroy_rcu(), so this metrics > > will be released twice... > > And even if there was a leak here, it's illegal to free this > metrics memory synchronously since it is RCU protected. Yeah, I noticed that today, but I don't think that's the problem we're seeing here. > That's why it normally goes through fib6_info_destroy_rcu(). > > Sabrina, I'm going to revert your changes unless I see some > progress here by the end of today. Yeah, I'm fine with a revert, we can fix the leak later. syzbot hasn't found a reproducer so I'm not sure it's the same issue, but I ran into this: we can create a route, start using it, and then give it some metrics. In that case, we'll hit rt6_set_from() with the default metrics, so we don't refcount them. Then fib6_metric_set() will assign the new metrics to the parent route. Then fib6_drop_pcpu_from will see that the parent route has non-default metrics, and try to release this, but the percpu copy doesn't actually hold a reference. Bandaid would be to put a DST_METRICS_REFCOUNTED check in fib6_drop_pcpu_from(). Looking at rt6_set_from(), it seems we can also do dst_init_metrics with the old metrics, then refcount the new metrics. And I'm not sure whether the refcount_set in fib6_metric_set() can't be reordered so that rt6_set_from() might see the new metrics pointer, increment the refcount, then fib6_metric_set() would do its refcount_set, stepping over the previous increment. -- Sabrina ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2018-08-02 5:17 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-07-31 12:31 KASAN: use-after-free Read in rtnetlink_put_metrics syzbot 2018-07-31 12:41 ` Eric Dumazet 2018-07-31 13:40 ` Sabrina Dubroca 2018-07-31 21:53 ` David Miller 2018-07-31 23:03 ` Cong Wang 2018-08-01 8:15 ` Sabrina Dubroca 2018-08-01 8:28 ` David Ahern 2018-08-02 5:23 ` Cong Wang 2018-08-01 18:46 ` David Miller 2018-08-01 19:26 ` Sabrina Dubroca
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