syzbot

 sign-in | mailing list | source | docs
🐞 Open [1588]
≡ Subsystems
🐞 Fixed [6318]
🐞 Invalid [16085]
⬇ Missing Backports [191]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

KASAN: slab-out-of-bounds Write in enqueue_timer

Status: moderation: reported on 2025/06/22 09:47
Subsystems: bluetooth
[Documentation on labels]
Reported-by: syzbot+8048f9c5244d13b39683@syzkaller.appspotmail.com
First crash: 4d13h, last: 4d13h
▶ ▼ Similar bugs (7)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-54 KASAN: use-after-free Write in enqueue_timer (2) C 5369 27d 125d 0/2 upstream: reported C repro on 2025/02/17 15:17
android-54 KASAN: use-after-free Write in enqueue_timer C 4288 354d 861d 0/2 auto-obsoleted due to no activity on 2024/09/11 16:22
upstream KASAN: slab-use-after-free Write in enqueue_timer net 18 768d 784d 0/29 auto-obsoleted due to no activity on 2023/08/22 15:17
upstream KASAN: use-after-free Write in enqueue_timer net 1 950d 950d 22/29 fixed on 2023/02/24 13:50
android-5-15 KASAN: use-after-free Write in enqueue_timer 1 521d 521d 0/2 auto-obsoleted due to no activity on 2024/04/17 12:01
android-6-1 KASAN: use-after-free Write in enqueue_timer origin:lts C 139 11h03m 332d 0/2 upstream: reported C repro on 2024/07/25 13:16
upstream KASAN: invalid-access Write in enqueue_timer ext4 20 1565d 1587d 0/29 auto-closed as invalid on 2021/07/08 00:48

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in hlist_add_head include/linux/list.h:1026 [inline]
BUG: KASAN: slab-out-of-bounds in enqueue_timer+0x515/0x540 kernel/time/timer.c:616
Write of size 8 at addr ffff8880343592e0 by task kworker/u9:0/3781

CPU: 0 UID: 0 PID: 3781 Comm: kworker/u9:0 Tainted: G     U    I         6.16.0-rc2-syzkaller-00047-g52da431bf03b #0 PREEMPT(full) 
Tainted: [U]=USER, [I]=FIRMWARE_WORKAROUND
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci0 hci_devcd_rx
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xcd/0x680 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 hlist_add_head include/linux/list.h:1026 [inline]
 enqueue_timer+0x515/0x540 kernel/time/timer.c:616
 internal_add_timer kernel/time/timer.c:645 [inline]
 __mod_timer+0x8ce/0xd30 kernel/time/timer.c:1136
 add_timer_global+0x8a/0xc0 kernel/time/timer.c:1283
 __queue_delayed_work+0x33a/0x460 kernel/workqueue.c:2526
 queue_delayed_work_on+0x1b5/0x200 kernel/workqueue.c:2561
 queue_delayed_work include/linux/workqueue.h:677 [inline]
 hci_devcd_handle_pkt_init net/bluetooth/coredump.c:207 [inline]
 hci_devcd_rx+0x1202/0x1780 net/bluetooth/coredump.c:351
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 13:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_node_track_caller_noprof+0x221/0x510 mm/slub.c:4347
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:601
 __alloc_skb+0x166/0x380 net/core/skbuff.c:670
 alloc_skb include/linux/skbuff.h:1336 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x2b1/0xcf0 drivers/net/netdevsim/dev.c:851
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 13:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x2b4/0x4d0 mm/slub.c:4842
 skb_kfree_head net/core/skbuff.c:1048 [inline]
 skb_free_head+0x114/0x210 net/core/skbuff.c:1060
 skb_release_data+0x776/0x9c0 net/core/skbuff.c:1087
 skb_release_all net/core/skbuff.c:1152 [inline]
 __kfree_skb net/core/skbuff.c:1166 [inline]
 consume_skb net/core/skbuff.c:1398 [inline]
 consume_skb+0xbf/0x100 net/core/skbuff.c:1392
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline]
 nsim_dev_trap_report_work+0x8bd/0xcf0 drivers/net/netdevsim/dev.c:851
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888034358000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 736 bytes to the right of
 allocated 4096-byte region [ffff888034358000, ffff888034359000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x34358
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b842140 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b842140 dead000000000122 0000000000000000
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000d0d601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 13, tgid 13 (kworker/u8:1), ts 1469294891901, free_ts 1469154874477
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab mm/slub.c:2619 [inline]
 new_slab+0x23b/0x330 mm/slub.c:2673
 ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_node_track_caller_noprof+0x2ee/0x510 mm/slub.c:4347
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:601
 __alloc_skb+0x166/0x380 net/core/skbuff.c:670
 alloc_skb include/linux/skbuff.h:1336 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x2b1/0xcf0 drivers/net/netdevsim/dev.c:851
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 5828 tgid 5828 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
 __folio_put+0x329/0x450 mm/swap.c:112
 folio_put include/linux/mm.h:1356 [inline]
 put_page include/linux/mm.h:1425 [inline]
 put_netmem net/core/skbuff.c:7375 [inline]
 skb_page_unref include/linux/skbuff_ref.h:43 [inline]
 __skb_frag_unref include/linux/skbuff_ref.h:56 [inline]
 skb_release_data+0x7fb/0x9c0 net/core/skbuff.c:1081
 skb_release_all net/core/skbuff.c:1152 [inline]
 __kfree_skb+0x4f/0x70 net/core/skbuff.c:1166
 tcp_wmem_free_skb include/net/tcp.h:309 [inline]
 tcp_rtx_queue_unlink_and_free include/net/tcp.h:2164 [inline]
 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3441 [inline]
 tcp_ack+0x19b2/0x5c90 net/ipv4/tcp_input.c:4049
 tcp_rcv_established+0xda1/0x22e0 net/ipv4/tcp_input.c:6216
 tcp_v4_do_rcv+0x5ca/0xa90 net/ipv4/tcp_ipv4.c:1925
 sk_backlog_rcv include/net/sock.h:1148 [inline]
 __release_sock+0x31b/0x400 net/core/sock.c:3213
 release_sock+0x5a/0x220 net/core/sock.c:3767
 tcp_sendmsg+0x38/0x50 net/ipv4/tcp.c:1397
 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 sock_write_iter+0x4aa/0x5b0 net/socket.c:1131
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x6c7/0x1150 fs/read_write.c:686
 ksys_write+0x1f8/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888034359180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888034359200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888034359280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                       ^
 ffff888034359300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888034359380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/18 09:40 upstream 52da431bf03b 74c9d252 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto KASAN: slab-out-of-bounds Write in enqueue_timer
* Struck through repros no longer work on HEAD.