KASAN: use-after-free Read in usb_udc_uevent

KASAN: use-after-free Read in usb_udc_uevent

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    ffeb595d Merge tag 'powerpc-5.7-6' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17f7f2b1100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9ac87c7c2ba15abf
dashboard link: https://syzkaller.appspot.com/bug?extid=b0de012ceb1e2a97891b
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)

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+b0de012ceb1e2a97891b@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in usb_udc_uevent+0xac/0x120 drivers/usb/gadget/udc/core.c:1593
Read of size 8 at addr ffff888091a7c050 by task systemd-udevd/14223

CPU: 1 PID: 14223 Comm: systemd-udevd Not tainted 5.7.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x74/0x5c0 mm/kasan/report.c:382
 __kasan_report+0x103/0x1a0 mm/kasan/report.c:511
 kasan_report+0x4d/0x80 mm/kasan/common.c:625

Allocated by task 14178:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
 kmem_cache_alloc_trace+0x234/0x300 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 dev_new drivers/usb/gadget/legacy/raw_gadget.c:182 [inline]
 raw_open+0x87/0x500 drivers/usb/gadget/legacy/raw_gadget.c:372
 misc_open+0x346/0x3c0 drivers/char/misc.c:141
 chrdev_open+0x498/0x580 fs/char_dev.c:414
 do_dentry_open+0x82e/0x10b0 fs/open.c:797
 do_open fs/namei.c:3229 [inline]
 path_openat+0x2790/0x38b0 fs/namei.c:3346
 do_filp_open+0x191/0x3a0 fs/namei.c:3373
 do_sys_openat2+0x463/0x770 fs/open.c:1148
 do_sys_open fs/open.c:1164 [inline]
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1170 [inline]
 __se_sys_open fs/open.c:1168 [inline]
 __x64_sys_open+0x1af/0x1e0 fs/open.c:1168
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 14174:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0x125/0x190 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 raw_release+0x130/0x1e0 drivers/usb/gadget/legacy/raw_gadget.c:411
 __fput+0x2ed/0x750 fs/file_table.c:280
 task_work_run+0x147/0x1d0 kernel/task_work.c:123
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x5ef/0x1f80 kernel/exit.c:796
 do_group_exit+0x15e/0x2c0 kernel/exit.c:894
 get_signal+0x13cf/0x1d60 kernel/signal.c:2739
 do_signal+0x33/0x610 arch/x86/kernel/signal.c:784
 exit_to_usermode_loop arch/x86/entry/common.c:161 [inline]
 prepare_exit_to_usermode+0x32a/0x600 arch/x86/entry/common.c:196
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff888091a7c000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 80 bytes inside of
 4096-byte region [ffff888091a7c000, ffff888091a7d000)
The buggy address belongs to the page:
page:ffffea0002469f00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0002469f00 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0001043588 ffffea0001258b88 ffff8880aa402000
raw: 0000000000000000 ffff888091a7c000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888091a7bf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888091a7bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888091a7c000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888091a7c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091a7c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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#status for how to communicate with syzbot.

Re: [syzbot] KASAN: use-after-free Read in usb_udc_uevent

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    cb71b93c2dc3 Add linux-next specific files for 20220628
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=172591aa080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=badbc1adb2d582eb
dashboard link: https://syzkaller.appspot.com/bug?extid=b0de012ceb1e2a97891b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13ab4d62080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0de012ceb1e2a97891b@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in usb_udc_uevent+0x11f/0x130 drivers/usb/gadget/udc/core.c:1732
Read of size 8 at addr ffff888078ce2050 by task udevd/2968

CPU: 1 PID: 2968 Comm: udevd Not tainted 5.19.0-rc4-next-20220628-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:317 [inline]
 print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
 kasan_report+0xbe/0x1f0 mm/kasan/report.c:495
 usb_udc_uevent+0x11f/0x130 drivers/usb/gadget/udc/core.c:1732
 dev_uevent+0x290/0x770 drivers/base/core.c:2424
 uevent_show+0x1b8/0x380 drivers/base/core.c:2480
 dev_attr_show+0x4b/0x90 drivers/base/core.c:2183
 sysfs_kf_seq_show+0x219/0x3d0 fs/sysfs/file.c:59
 seq_read_iter+0x4f5/0x1280 fs/seq_file.c:230
 kernfs_fop_read_iter+0x506/0x6e0 fs/kernfs/file.c:235
 call_read_iter include/linux/fs.h:2182 [inline]
 new_sync_read+0x314/0x560 fs/read_write.c:401
 vfs_read+0x492/0x5d0 fs/read_write.c:482
 ksys_read+0x127/0x250 fs/read_write.c:620
 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+0x46/0xb0
RIP: 0033:0x7f996d1258fe
Code: c0 e9 e6 fe ff ff 50 48 8d 3d 0e c7 09 00 e8 c9 cf 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
RSP: 002b:00007ffcfcbe6368 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000055ca13b297a0 RCX: 00007f996d1258fe
RDX: 0000000000001000 RSI: 000055ca13b5a4e0 RDI: 000000000000000c
RBP: 00007f996d1f2380 R08: 000000000000000c R09: 00007f996d1f5a60
R10: 0000000000000800 R11: 0000000000000246 R12: 000055ca13b297a0
R13: 0000000000000d68 R14: 00007f996d1f1780 R15: 0000000000000d68
 </TASK>

Allocated by task 4797:
 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_kmalloc mm/kasan/common.c:515 [inline]
 ____kasan_kmalloc mm/kasan/common.c:474 [inline]
 __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:733 [inline]
 dev_new drivers/usb/gadget/legacy/raw_gadget.c:191 [inline]
 raw_open+0x87/0x500 drivers/usb/gadget/legacy/raw_gadget.c:385
 misc_open+0x376/0x4a0 drivers/char/misc.c:143
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x4a1/0x11f0 fs/open.c:878
 do_open fs/namei.c:3520 [inline]
 path_openat+0x1c71/0x2930 fs/namei.c:3653
 do_filp_open+0x1aa/0x400 fs/namei.c:3680
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1308
 do_sys_open fs/open.c:1324 [inline]
 __do_sys_openat fs/open.c:1340 [inline]
 __se_sys_openat fs/open.c:1335 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1335
 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+0x46/0xb0

Freed by task 4797:
 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+0x166/0x1c0 mm/kasan/common.c:328
 kasan_slab_free include/linux/kasan.h:200 [inline]
 slab_free_hook mm/slub.c:1754 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1780
 slab_free mm/slub.c:3534 [inline]
 kfree+0xe2/0x4d0 mm/slub.c:4562
 kref_put include/linux/kref.h:65 [inline]
 raw_release+0x219/0x290 drivers/usb/gadget/legacy/raw_gadget.c:424
 __fput+0x277/0x9d0 fs/file_table.c:317
 task_work_run+0xdd/0x1a0 kernel/task_work.c:177
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xaf1/0x29f0 kernel/exit.c:795
 do_group_exit+0xd2/0x2f0 kernel/exit.c:925
 get_signal+0x2542/0x2600 kernel/signal.c:2857
 arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869
 exit_to_user_mode_loop kernel/entry/common.c:166 [inline]
 exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff888078ce2000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 80 bytes inside of
 4096-byte region [ffff888078ce2000, ffff888078ce3000)

The buggy address belongs to the physical page:
page:ffffea0001e33800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x78ce0
head:ffffea0001e33800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888011842140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3618, tgid 3618 (syz-executor.2), ts 66675676094, free_ts 28120915618
 prep_new_page mm/page_alloc.c:2535 [inline]
 get_page_from_freelist+0x210d/0x3a30 mm/page_alloc.c:4282
 __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5506
 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2280
 alloc_slab_page mm/slub.c:1824 [inline]
 allocate_slab+0x27e/0x3d0 mm/slub.c:1969
 new_slab mm/slub.c:2029 [inline]
 ___slab_alloc+0x89d/0xef0 mm/slub.c:3031
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
 slab_alloc_node mm/slub.c:3209 [inline]
 slab_alloc mm/slub.c:3251 [inline]
 kmem_cache_alloc_trace+0x323/0x3e0 mm/slub.c:3282
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:733 [inline]
 kobject_uevent_env+0x230/0x1640 lib/kobject_uevent.c:524
 netdev_queue_add_kobject net/core/net-sysfs.c:1677 [inline]
 netdev_queue_update_kobjects+0x3d1/0x4e0 net/core/net-sysfs.c:1718
 register_queue_kobjects net/core/net-sysfs.c:1779 [inline]
 netdev_register_kobject+0x330/0x400 net/core/net-sysfs.c:2019
 register_netdevice+0xd9d/0x15e0 net/core/dev.c:10065
 bond_newlink drivers/net/bonding/bond_netlink.c:560 [inline]
 bond_newlink+0x47/0xa0 drivers/net/bonding/bond_netlink.c:550
 rtnl_newlink_create net/core/rtnetlink.c:3363 [inline]
 __rtnl_newlink+0x1087/0x17e0 net/core/rtnetlink.c:3580
 rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3593
 rtnetlink_rcv_msg+0x43a/0xc90 net/core/rtnetlink.c:6089
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1453 [inline]
 free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1503
 free_unref_page_prepare mm/page_alloc.c:3383 [inline]
 free_unref_page+0x19/0x4d0 mm/page_alloc.c:3479
 __unfreeze_partials+0x17c/0x1a0 mm/slub.c:2548
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:736 [inline]
 kmem_cache_alloc_bulk+0x383/0x730 mm/slub.c:3735
 mt_alloc_bulk lib/maple_tree.c:151 [inline]
 mas_alloc_nodes+0x2b0/0x6b0 lib/maple_tree.c:1244
 mas_preallocate+0xff/0x2d0 lib/maple_tree.c:5662
 __vma_adjust+0x226/0x1900 mm/mmap.c:765
 vma_adjust include/linux/mm.h:2678 [inline]
 __split_vma+0x295/0x530 mm/mmap.c:2305
 split_vma+0x9f/0xe0 mm/mmap.c:2335
 mprotect_fixup+0x746/0x960 mm/mprotect.c:613
 do_mprotect_pkey+0x70f/0xa80 mm/mprotect.c:781
 __do_sys_mprotect mm/mprotect.c:808 [inline]
 __se_sys_mprotect mm/mprotect.c:805 [inline]
 __x64_sys_mprotect+0x74/0xb0 mm/mprotect.c:805
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80

Memory state around the buggy address:
 ffff888078ce1f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888078ce1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888078ce2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888078ce2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888078ce2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Re: [syzbot] KASAN: use-after-free Read in usb_udc_uevent

[Alan Stern]

On Wed, Jul 20, 2022 at 11:03:24AM -0700, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    cb71b93c2dc3 Add linux-next specific files for 20220628
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=172591aa080000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=badbc1adb2d582eb
> dashboard link: https://syzkaller.appspot.com/bug?extid=b0de012ceb1e2a97891b
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13ab4d62080000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b0de012ceb1e2a97891b@syzkaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: use-after-free in usb_udc_uevent+0x11f/0x130 drivers/usb/gadget/udc/core.c:1732
> Read of size 8 at addr ffff888078ce2050 by task udevd/2968
> 
> CPU: 1 PID: 2968 Comm: udevd Not tainted 5.19.0-rc4-next-20220628-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>  print_address_description mm/kasan/report.c:317 [inline]
>  print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
>  kasan_report+0xbe/0x1f0 mm/kasan/report.c:495
>  usb_udc_uevent+0x11f/0x130 drivers/usb/gadget/udc/core.c:1732
>  dev_uevent+0x290/0x770 drivers/base/core.c:2424
>  uevent_show+0x1b8/0x380 drivers/base/core.c:2480

It looks like the usb_udc_uevent call races with gadget removal.  The 
problem is that usb_udc_uevent accesses udc->driver but does not hold 
the udc_lock mutex (which protects this field) while doing so.

Alan Stern

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/ cb71b93c2dc3

Index: usb-devel/drivers/usb/gadget/udc/core.c
===================================================================
--- usb-devel.orig/drivers/usb/gadget/udc/core.c
+++ usb-devel/drivers/usb/gadget/udc/core.c
@@ -1728,13 +1728,14 @@ static int usb_udc_uevent(struct device
 		return ret;
 	}
 
-	if (udc->driver) {
+	mutex_lock(&udc_lock);
+	if (udc->driver)
 		ret = add_uevent_var(env, "USB_UDC_DRIVER=%s",
 				udc->driver->function);
-		if (ret) {
-			dev_err(dev, "failed to add uevent USB_UDC_DRIVER\n");
-			return ret;
-		}
+	mutex_unlock(&udc_lock);
+	if (ret) {
+		dev_err(dev, "failed to add uevent USB_UDC_DRIVER\n");
+		return ret;
 	}
 
 	return 0;

Re: [syzbot] KASAN: use-after-free Read in usb_udc_uevent

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+b0de012ceb1e2a97891b@syzkaller.appspotmail.com

Tested on:

commit:         cb71b93c Add linux-next specific files for 20220628
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/
console output: https://syzkaller.appspot.com/x/log.txt?x=1124f6d6080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=badbc1adb2d582eb
dashboard link: https://syzkaller.appspot.com/bug?extid=b0de012ceb1e2a97891b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=177cc2ba080000

Note: testing is done by a robot and is best-effort only.