syzbot


KASAN: use-after-free Read in skb_dequeue

Status: upstream: reported syz repro on 2021/08/16 16:14
Reported-by: syzbot+2f3a0be2a3fef0e262a9@syzkaller.appspotmail.com
First crash: 476d, last: 476d
similar bugs (6):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-49 KASAN: use-after-free Read in skb_dequeue (2) 8 1587d 1752d 0/3 auto-closed as invalid on 2019/02/22 12:37
upstream general protection fault in skb_dequeue (2) C inconclusive done 9 421d 506d 0/24 auto-closed as invalid on 2022/10/03 17:36
upstream KASAN: use-after-free Read in skb_dequeue C 4 1628d 1629d 9/24 fixed on 2018/07/09 18:05
linux-4.19 KASAN: use-after-free Read in skb_dequeue syz done 1 649d 854d 1/1 fixed on 2021/03/29 19:17
android-44 KASAN: use-after-free Read in skb_dequeue 1 1559d 1559d 0/2 auto-closed as invalid on 2019/02/25 16:09
linux-4.19 KASAN: use-after-free Read in skb_dequeue (2) C done 2 447d 477d 1/1 fixed on 2021/10/15 14:38

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __skb_unlink include/linux/skbuff.h:2051 [inline]
BUG: KASAN: use-after-free in __skb_dequeue include/linux/skbuff.h:2070 [inline]
BUG: KASAN: use-after-free in skb_dequeue+0xad/0x180 net/core/skbuff.c:3057
Read of size 8 at addr ffff8881e08bfc80 by task kworker/u5:6/408

CPU: 0 PID: 408 Comm: kworker/u5:6 Not tainted 5.4.125-syzkaller-00008-ga8f2bcabf9c5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci4 hci_rx_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x24e lib/dump_stack.c:118
 print_address_description+0x9b/0x650 mm/kasan/report.c:384
 __kasan_report+0x182/0x260 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 __skb_unlink include/linux/skbuff.h:2051 [inline]
 __skb_dequeue include/linux/skbuff.h:2070 [inline]
 skb_dequeue+0xad/0x180 net/core/skbuff.c:3057
 hci_rx_work+0x620/0x780 net/bluetooth/hci_core.c:4463
 process_one_work+0x679/0x1030 kernel/workqueue.c:2277
 worker_thread+0xa6f/0x1400 kernel/workqueue.c:2423
 kthread+0x30f/0x330 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 466:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x137/0x1e0 mm/kasan/common.c:529
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2821 [inline]
 slab_alloc mm/slub.c:2829 [inline]
 kmem_cache_alloc+0x115/0x290 mm/slub.c:2834
 kmem_cache_alloc_node include/linux/slab.h:427 [inline]
 __alloc_skb+0x75/0x4d0 net/core/skbuff.c:198
 alloc_skb include/linux/skbuff.h:1060 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
 h4_recv_buf+0x274/0xd00 drivers/bluetooth/hci_h4.c:182
 h4_recv+0xf4/0x1b0 drivers/bluetooth/hci_h4.c:116
 hci_uart_tty_receive+0x275/0x460 drivers/bluetooth/hci_ldisc.c:613
 tiocsti drivers/tty/tty_io.c:2197 [inline]
 tty_ioctl+0xd48/0x1710 drivers/tty/tty_io.c:2573
 do_vfs_ioctl+0x76a/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xcb/0x1e0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 408:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x18a/0x240 mm/kasan/common.c:487
 slab_free_hook mm/slub.c:1454 [inline]
 slab_free_freelist_hook+0x7b/0x150 mm/slub.c:1492
 slab_free mm/slub.c:3072 [inline]
 kmem_cache_free+0xb8/0x5f0 mm/slub.c:3088
 hci_event_packet+0xa284/0x22220 net/bluetooth/hci_event.c:6067
 hci_rx_work+0x287/0x780 net/bluetooth/hci_core.c:4498
 process_one_work+0x679/0x1030 kernel/workqueue.c:2277
 worker_thread+0xa6f/0x1400 kernel/workqueue.c:2423
 kthread+0x30f/0x330 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881e08bfc80
 which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 0 bytes inside of
 240-byte region [ffff8881e08bfc80, ffff8881e08bfd70)
The buggy address belongs to the page:
page:ffffea0007822fc0 refcount:1 mapcount:0 mapping:ffff8881f1dde280 index:0x0
flags: 0x8000000000000200(slab)
raw: 8000000000000200 dead000000000100 dead000000000122 ffff8881f1dde280
raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x19a/0x380 mm/page_alloc.c:2171
 get_page_from_freelist+0x550/0x8b0 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x3a2/0x880 mm/page_alloc.c:4855
 alloc_slab_page+0x39/0x3e0 mm/slub.c:342
 allocate_slab mm/slub.c:1675 [inline]
 new_slab+0x97/0x460 mm/slub.c:1741
 new_slab_objects mm/slub.c:2498 [inline]
 ___slab_alloc+0x330/0x4c0 mm/slub.c:2659
 __slab_alloc mm/slub.c:2699 [inline]
 slab_alloc_node mm/slub.c:2784 [inline]
 slab_alloc mm/slub.c:2829 [inline]
 kmem_cache_alloc+0x18b/0x290 mm/slub.c:2834
 kmem_cache_alloc_node include/linux/slab.h:427 [inline]
 __alloc_skb+0x75/0x4d0 net/core/skbuff.c:198
 alloc_skb include/linux/skbuff.h:1060 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
 hci_prepare_cmd net/bluetooth/hci_request.c:296 [inline]
 hci_req_add_ev+0xa4/0x3c0 net/bluetooth/hci_request.c:330
 bredr_init net/bluetooth/hci_core.c:200 [inline]
 hci_init1_req+0x134/0x270 net/bluetooth/hci_core.c:256
 __hci_req_sync+0x174/0x8a0 net/bluetooth/hci_request.c:205
 __hci_init net/bluetooth/hci_core.c:868 [inline]
 hci_dev_do_open+0xafe/0x1670 net/bluetooth/hci_core.c:1528
 hci_power_on+0x155/0x580 net/bluetooth/hci_core.c:2200
 process_one_work+0x679/0x1030 kernel/workqueue.c:2277
 worker_thread+0xa6f/0x1400 kernel/workqueue.c:2423
 kthread+0x30f/0x330 kernel/kthread.c:268
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 free_pcp_prepare+0x1a9/0x270 mm/page_alloc.c:1233
 free_unref_page_prepare mm/page_alloc.c:3085 [inline]
 free_unref_page mm/page_alloc.c:3134 [inline]
 free_the_page mm/page_alloc.c:4915 [inline]
 __free_pages+0x9c/0x250 mm/page_alloc.c:4923
 selinux_genfs_get_sid security/selinux/hooks.c:1367 [inline]
 inode_doinit_with_dentry+0xb34/0x11d0 security/selinux/hooks.c:1562
 security_d_instantiate+0xa5/0x100 security/security.c:1882
 d_instantiate+0x51/0x90 fs/dcache.c:1954
 debugfs_create_dir+0x1bc/0x3f0 fs/debugfs/inode.c:571
 hci_register_dev+0x297/0x710 net/bluetooth/hci_core.c:3333
 hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:682 [inline]
 hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:706 [inline]
 hci_uart_tty_ioctl+0x89e/0xa10 drivers/bluetooth/hci_ldisc.c:760
 tty_ioctl+0xf68/0x1710 drivers/tty/tty_io.c:2666
 do_vfs_ioctl+0x76a/0x1720 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:742 [inline]
 __do_sys_ioctl fs/ioctl.c:749 [inline]
 __se_sys_ioctl fs/ioctl.c:747 [inline]
 __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747
 do_syscall_64+0xcb/0x1e0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Memory state around the buggy address:
 ffff8881e08bfb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e08bfc00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
>ffff8881e08bfc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8881e08bfd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff8881e08bfd80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 408 Comm: kworker/u5:6 Tainted: G    B             5.4.125-syzkaller-00008-ga8f2bcabf9c5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci4 hci_rx_work
RIP: 0010:__write_once_size include/linux/compiler.h:293 [inline]
RIP: 0010:__skb_unlink include/linux/skbuff.h:2054 [inline]
RIP: 0010:__skb_dequeue include/linux/skbuff.h:2070 [inline]
RIP: 0010:skb_dequeue+0xe8/0x180 net/core/skbuff.c:3057
Code: 80 3c 38 00 74 05 e8 87 8f 1e fe 49 8b 5c 24 08 4d 8d 6e 08 ba 10 00 00 00 4c 89 e7 31 f6 e8 3f 62 1e fe 4c 89 e8 48 c1 e8 03 <42> 80 3c 38 00 74 08 4c 89 ef e8 d9 8f 1e fe 49 89 5e 08 48 89 d8
RSP: 0018:ffff8881e1adfc50 EFLAGS: 00010002
RAX: 0000000000000001 RBX: ffff8881e08bfc80 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffff8881e08bfc90
RBP: 1ffff1103bed0172 R08: dffffc0000000000 R09: ffff8881e08bfc80
R10: ffffed103c117f92 R11: 00000000000000fb R12: ffff8881e08bfc80
R13: 0000000000000008 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005198f0 CR3: 00000001e6370000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 hci_rx_work+0x620/0x780 net/bluetooth/hci_core.c:4463
 process_one_work+0x679/0x1030 kernel/workqueue.c:2277
 worker_thread+0xa6f/0x1400 kernel/workqueue.c:2423
 kthread+0x30f/0x330 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace 29535e1e0975b2a5 ]---
RIP: 0010:__write_once_size include/linux/compiler.h:293 [inline]
RIP: 0010:__skb_unlink include/linux/skbuff.h:2054 [inline]
RIP: 0010:__skb_dequeue include/linux/skbuff.h:2070 [inline]
RIP: 0010:skb_dequeue+0xe8/0x180 net/core/skbuff.c:3057
Code: 80 3c 38 00 74 05 e8 87 8f 1e fe 49 8b 5c 24 08 4d 8d 6e 08 ba 10 00 00 00 4c 89 e7 31 f6 e8 3f 62 1e fe 4c 89 e8 48 c1 e8 03 <42> 80 3c 38 00 74 08 4c 89 ef e8 d9 8f 1e fe 49 89 5e 08 48 89 d8
RSP: 0018:ffff8881e1adfc50 EFLAGS: 00010002
RAX: 0000000000000001 RBX: ffff8881e08bfc80 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffff8881e08bfc90
RBP: 1ffff1103bed0172 R08: dffffc0000000000 R09: ffff8881e08bfc80
R10: ffffed103c117f92 R11: 00000000000000fb R12: ffff8881e08bfc80
R13: 0000000000000008 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005198f0 CR3: 00000001e6370000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	80 3c 38 00          	cmpb   $0x0,(%rax,%rdi,1)
   4:	74 05                	je     0xb
   6:	e8 87 8f 1e fe       	callq  0xfe1e8f92
   b:	49 8b 5c 24 08       	mov    0x8(%r12),%rbx
  10:	4d 8d 6e 08          	lea    0x8(%r14),%r13
  14:	ba 10 00 00 00       	mov    $0x10,%edx
  19:	4c 89 e7             	mov    %r12,%rdi
  1c:	31 f6                	xor    %esi,%esi
  1e:	e8 3f 62 1e fe       	callq  0xfe1e6262
  23:	4c 89 e8             	mov    %r13,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
  2a:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ef             	mov    %r13,%rdi
  34:	e8 d9 8f 1e fe       	callq  0xfe1e9012
  39:	49 89 5e 08          	mov    %rbx,0x8(%r14)
  3d:	48 89 d8             	mov    %rbx,%rax

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-android-5-4-kasan 2021/08/16 16:13 android12-5.4 a8f2bcabf9c5 6652437d .config log report syz KASAN: use-after-free Read in skb_dequeue
* Struck through repros no longer work on HEAD.