* [syzbot] [fs?] [mm?] KASAN: slab-use-after-free Read in trace_event_raw_event_hugetlbfs__inode
@ 2026-10-28 22:20 syzbot
0 siblings, 0 replies; only message in thread
From: syzbot @ 2026-10-28 22:20 UTC (permalink / raw)
To: linux-fsdevel, linux-kernel, linux-mm, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: d135ab453a74 Merge tag 'backlight-next-7.4' of git://git.k..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=142de17f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=6f2905533069b0f5
dashboard link: https://syzkaller.appspot.com/bug?extid=91e1fc35f51774c479b2
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17432995580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+91e1fc35f51774c479b2@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in do_trace_event_raw_event_hugetlbfs__inode include/trace/events/hugetlbfs.h:36 [inline]
BUG: KASAN: slab-use-after-free in trace_event_raw_event_hugetlbfs__inode+0x45b/0x4c0 include/trace/events/hugetlbfs.h:36
Read of size 4 at addr ffff888038850010 by task syz-executor952/6134
CPU: 3 UID: 0 PID: 6134 Comm: syz-executor952 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
do_trace_event_raw_event_hugetlbfs__inode include/trace/events/hugetlbfs.h:36 [inline]
trace_event_raw_event_hugetlbfs__inode+0x45b/0x4c0 include/trace/events/hugetlbfs.h:36
__do_trace_hugetlbfs_free_inode include/trace/events/hugetlbfs.h:75 [inline]
trace_hugetlbfs_free_inode include/trace/events/hugetlbfs.h:75 [inline]
hugetlbfs_free_inode+0x15e/0x1f0 fs/hugetlbfs/inode.c:1182
i_callback+0x46/0x80 fs/inode.c:317
rcu_do_batch kernel/rcu/tree.c:2650 [inline]
rcu_core+0x5f0/0x1220 kernel/rcu/tree.c:2919
handle_softirqs+0x216/0xa20 kernel/softirq.c:669
__do_softirq kernel/softirq.c:703 [inline]
invoke_softirq kernel/softirq.c:542 [inline]
__irq_exit_rcu+0x178/0x220 kernel/softirq.c:786
irq_exit_rcu+0x9/0x30 kernel/softirq.c:809
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:__sanitizer_cov_trace_pc+0x46/0x70 kernel/kcov.c:213
Code: 00 01 00 ff 74 1e f6 c4 01 74 44 a9 00 00 00 0f 75 3d f7 c1 00 00 00 f0 75 35 8b 82 44 17 00 00 85 c0 74 2b 8b 82 18 17 00 00 <83> f8 02 75 20 48 8b 8a 20 17 00 00 8b 92 1c 17 00 00 48 8b 01 48
RSP: 0018:ffffc900035dfd38 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc90000327df0 RCX: 0000000000000003
RDX: ffff8880311b0000 RSI: ffffffff82a3cf67 RDI: ffff8880311b0000
RBP: ffffc90000327df0 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88803b243da8 R15: 0000000000000000
__hlist_bl_del include/linux/list_bl.h:123 [inline]
___d_drop+0xe7/0x2d0 fs/dcache.c:584
__d_drop fs/dcache.c:591 [inline]
__d_drop fs/dcache.c:588 [inline]
d_delete+0xd1/0x280 fs/dcache.c:2785
d_delete_notify include/linux/fsnotify.h:379 [inline]
vfs_unlink+0x688/0xbd0 fs/namei.c:5676
filename_unlinkat+0x408/0x730 fs/namei.c:5731
__do_sys_unlink fs/namei.c:5766 [inline]
__se_sys_unlink fs/namei.c:5763 [inline]
__x64_sys_unlink+0x46/0x70 fs/namei.c:5763
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f62cdcc0047
Code: 1f 40 00 48 89 f2 31 c9 48 89 fe bf 9c ff ff ff e9 ce 5f 03 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 b8 57 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 d0 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007f62cc488088 EFLAGS: 00000202 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007ffd4150bf90 RCX: 00007f62cdcc0047
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f62cc488160
RBP: 0000000000000017 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000001b6 R11: 0000000000000202 R12: 00007f62cc4880a0
R13: 00007f62cdd315b8 R14: 00007f62cc4880e0 R15: 00007f62cc488160
</TASK>
Allocated by task 6134:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:426
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x2f8/0x6d0 mm/slub.c:5680
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
alloc_super fs/super.c:326 [inline]
sget_fc+0x1ba/0x1f60 fs/super.c:874
get_tree_super fs/super.c:1395 [inline]
get_tree_nodev+0x28/0x190 fs/super.c:1420
hugetlbfs_get_tree+0x1e7/0x2b0 fs/hugetlbfs/inode.c:1431
vfs_get_tree+0x92/0x320 fs/super.c:1943
fc_mount fs/namespace.c:1282 [inline]
do_new_mount_fc fs/namespace.c:3910 [inline]
do_new_mount fs/namespace.c:3986 [inline]
path_mount+0x7d0/0x2850 fs/namespace.c:4337
do_mount fs/namespace.c:4350 [inline]
__do_sys_mount fs/namespace.c:4565 [inline]
__se_sys_mount fs/namespace.c:4542 [inline]
__x64_sys_mount+0x293/0x310 fs/namespace.c:4542
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 855:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:264 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:296
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2780 [inline]
slab_free mm/slub.c:6630 [inline]
kfree+0x22b/0x6d0 mm/slub.c:6923
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3495
process_scheduled_works kernel/workqueue.c:3578 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3659
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Last potentially related work creation:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
insert_work+0x36/0x230 kernel/workqueue.c:2356
__queue_work+0xac1/0x16f0 kernel/workqueue.c:2546
queue_work_on+0x180/0x1e0 kernel/workqueue.c:2599
rcu_do_batch kernel/rcu/tree.c:2650 [inline]
rcu_core+0x5f0/0x1220 kernel/rcu/tree.c:2919
handle_softirqs+0x216/0xa20 kernel/softirq.c:669
__do_softirq kernel/softirq.c:703 [inline]
invoke_softirq kernel/softirq.c:542 [inline]
__irq_exit_rcu+0x178/0x220 kernel/softirq.c:786
irq_exit_rcu+0x9/0x30 kernel/softirq.c:809
instr_sysvec_call_function_single arch/x86/kernel/smp.c:267 [inline]
sysvec_call_function_single+0xa3/0xc0 arch/x86/kernel/smp.c:267
asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:681
Second to last potentially related work creation:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
__call_rcu_common.constprop.0+0x7b/0x2b0 kernel/rcu/tree.c:3287
put_super fs/super.c:432 [inline]
put_super+0x30e/0x420 fs/super.c:419
deactivate_locked_super+0xe5/0x130 fs/super.c:594
deactivate_super fs/super.c:614 [inline]
deactivate_super+0xea/0x110 fs/super.c:610
cleanup_mnt+0xb7/0x160 fs/namespace.c:1396
task_work_run+0x150/0x240 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
exit_to_user_mode_loop+0x1d8/0x700 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline]
do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888038850000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 16 bytes inside of
freed 4096-byte region [ffff888038850000, ffff888038851000)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x38850
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 ffff88801d443040 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801d443040 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5207, tgid 5207 (udevd), ts 22161561359
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1854
prep_new_page mm/page_alloc.c:1862 [inline]
get_page_from_freelist+0x1113/0x35e0 mm/page_alloc.c:3933
__alloc_frozen_pages_noprof+0x2f6/0x3190 mm/page_alloc.c:5429
alloc_slab_page mm/slub.c:3384 [inline]
allocate_slab mm/slub.c:3499 [inline]
new_slab+0xb1/0x6d0 mm/slub.c:3550
refill_objects+0xe3/0x410 mm/slub.c:7539
refill_sheaf mm/slub.c:2917 [inline]
__pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4811
alloc_from_pcs mm/slub.c:4887 [inline]
slab_alloc_node mm/slub.c:5021 [inline]
__kmalloc_cache_noprof+0x4ef/0x6d0 mm/slub.c:5676
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
kernfs_iop_get_link fs/kernfs/symlink.c:148 [inline]
kernfs_iop_get_link+0x65/0x1770 fs/kernfs/symlink.c:139
vfs_readlink+0x213/0x440 fs/namei.c:6431
do_readlinkat+0x250/0x370 fs/stat.c:587
__do_sys_readlink fs/stat.c:609 [inline]
__se_sys_readlink fs/stat.c:606 [inline]
__x64_sys_readlink+0x78/0xc0 fs/stat.c:606
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5196 tgid 5196 ts 22123403954 stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
__free_pages_prepare mm/page_alloc.c:1401 [inline]
__free_frozen_pages+0x7b4/0x1110 mm/page_alloc.c:2952
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:361
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4720 [inline]
slab_alloc_node mm/slub.c:5033 [inline]
__kmalloc_cache_noprof+0x278/0x6d0 mm/slub.c:5676
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
kernfs_fop_open+0x347/0x10f0 fs/kernfs/file.c:648
do_dentry_open+0x674/0x1470 fs/open.c:1000
vfs_open_consume+0xcc/0x460 fs/open.c:1131
do_open fs/namei.c:4845 [inline]
path_openat+0x1547/0x23f0 fs/namei.c:5010
do_file_open+0x20e/0x430 fs/namei.c:5039
do_sys_openat2+0x163/0x1d0 fs/open.c:1442
do_sys_open fs/open.c:1448 [inline]
__do_sys_openat fs/open.c:1464 [inline]
__se_sys_openat fs/open.c:1459 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1459
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff88803884ff00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
ffff88803884ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888038850000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888038850080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888038850100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 00 01 add %al,(%rcx)
2: 00 ff add %bh,%bh
4: 74 1e je 0x24
6: f6 c4 01 test $0x1,%ah
9: 74 44 je 0x4f
b: a9 00 00 00 0f test $0xf000000,%eax
10: 75 3d jne 0x4f
12: f7 c1 00 00 00 f0 test $0xf0000000,%ecx
18: 75 35 jne 0x4f
1a: 8b 82 44 17 00 00 mov 0x1744(%rdx),%eax
20: 85 c0 test %eax,%eax
22: 74 2b je 0x4f
24: 8b 82 18 17 00 00 mov 0x1718(%rdx),%eax
* 2a: 83 f8 02 cmp $0x2,%eax <-- trapping instruction
2d: 75 20 jne 0x4f
2f: 48 8b 8a 20 17 00 00 mov 0x1720(%rdx),%rcx
36: 8b 92 1c 17 00 00 mov 0x171c(%rdx),%edx
3c: 48 8b 01 mov (%rcx),%rax
3f: 48 rex.W
---
This report is generated by a bot. It may contain errors.
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