KASAN: use-after-free Read in tracing_open_file_tr

Status: upstream: reported C repro on 2026/10/17 06:12
Reported-by: syzbot+468dbb886f14e7ee05a5@syzkaller.appspotmail.com
First crash: 22d, last: 22d
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in tracing_open_file_tr 19 syz, C 1 15d 48d 0/2 upstream: reported C repro on 2026/09/21 10:22
linux-6.1 KASAN: use-after-free Read in tracing_open_file_tr 19 syz, C 6 5d10h 20d 0/3 upstream: reported C repro on 2026/10/19 01:40

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in tracing_open_file_tr+0x63/0x2f0 kernel/trace/trace.c:4876
Read of size 8 at addr ffff888024892d28 by task syz.2.65/4512

CPU: 1 PID: 4512 Comm: syz.2.65 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 tracing_open_file_tr+0x63/0x2f0 kernel/trace/trace.c:4876
 do_dentry_open+0x7f7/0xf90 fs/open.c:826
 do_open fs/namei.c:3659 [inline]
 path_openat+0x2718/0x2fb0 fs/namei.c:3793
 do_filp_open+0x1df/0x400 fs/namei.c:3820
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fe6ff8ee559
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe9f6a6498 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe6ffb75fa0 RCX: 00007fe6ff8ee559
RDX: 0000000000000002 RSI: 0000200000000200 RDI: ffffffffffffff9c
RBP: 00007fe6ff985ab8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe6ffb75fac R14: 00007fe6ffb75fa0 R15: 00007fe6ffb75fa0
 </TASK>

Allocated by task 4512:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x92/0xc0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x15d/0x280 mm/slub.c:3238
 trace_create_new_event+0x26/0x3d0 kernel/trace/trace_events.c:3013
 __trace_add_new_event kernel/trace/trace_events.c:3042 [inline]
 __add_event_to_tracers kernel/trace/trace_events.c:3766 [inline]
 trace_add_event_call+0xed/0x1c0 kernel/trace/trace_events.c:3083
 trace_probe_register_event_call+0x328/0x3e0 kernel/trace/trace_probe.c:1179
 __trace_eprobe_create+0xaaf/0xc80 kernel/trace/trace_eprobe.c:973
 trace_probe_create+0xc4/0x130 kernel/trace/trace_probe.c:1287
 create_dyn_event+0xa9/0x140 kernel/trace/trace_dynevent.c:152
 trace_parse_run_command+0x1a8/0x2c0 kernel/trace/trace.c:10201
 vfs_write+0x304/0xd70 fs/read_write.c:592
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 4513:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 tracing_release_file_tr+0xbd/0x100 kernel/trace/trace.c:4904
 __fput+0x212/0x8c0 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:184
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff888024892d00
 which belongs to the cache trace_event_file of size 96
The buggy address is located 40 bytes inside of
 96-byte region [ffff888024892d00, ffff888024892d60)
The buggy address belongs to the page:
page:ffffea0000922480 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x24892
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff8880178c5280
raw: 0000000000000000 0000000080200020 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4432, ts 84571852045, free_ts 81986289510
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0xf0/0x280 mm/slub.c:3238
 trace_create_new_event+0x26/0x3d0 kernel/trace/trace_events.c:3013
 __trace_add_new_event kernel/trace/trace_events.c:3042 [inline]
 __add_event_to_tracers kernel/trace/trace_events.c:3766 [inline]
 trace_add_event_call+0xed/0x1c0 kernel/trace/trace_events.c:3083
 trace_probe_register_event_call+0x328/0x3e0 kernel/trace/trace_probe.c:1179
 __trace_eprobe_create+0xaaf/0xc80 kernel/trace/trace_eprobe.c:973
 trace_probe_create+0xc4/0x130 kernel/trace/trace_probe.c:1287
 create_dyn_event+0xa9/0x140 kernel/trace/trace_dynevent.c:152
 trace_parse_run_command+0x1a8/0x2c0 kernel/trace/trace.c:10201
 vfs_write+0x304/0xd70 fs/read_write.c:592
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 free_slab mm/slub.c:2020 [inline]
 discard_slab mm/slub.c:2026 [inline]
 __unfreeze_partials+0x188/0x1e0 mm/slub.c:2512
 put_cpu_partial+0x12d/0x190 mm/slub.c:2592
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 kmem_cache_alloc_node+0x184/0x2c0 mm/slub.c:3261
 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1162 [inline]
 mld_newpack+0x12f/0xba0 net/ipv6/mcast.c:1773
 add_grhead net/ipv6/mcast.c:1884 [inline]
 add_grec+0x1364/0x1840 net/ipv6/mcast.c:2023
 mld_send_cr net/ipv6/mcast.c:2146 [inline]
 mld_ifc_work+0x6f2/0xd60 net/ipv6/mcast.c:2688
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334

Memory state around the buggy address:
 ffff888024892c00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888024892c80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff888024892d00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                  ^
 ffff888024892d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888024892e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/17 11:10 linux-5.15.y 792fbe1537d8 432c0077 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in tracing_open_file_tr
2026/10/17 06:11 linux-5.15.y 792fbe1537d8 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in tracing_open_file_tr
* Struck through repros no longer work on HEAD.