==================================================================
BUG: KASAN: out-of-bounds in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: out-of-bounds in atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
BUG: KASAN: out-of-bounds in put_bh include/linux/buffer_head.h:304 [inline]
BUG: KASAN: out-of-bounds in end_buffer_read_sync+0xc3/0xe0 fs/buffer.c:161
Write of size 4 at addr ffffc900048ef700 by task kworker/u8:4/59
CPU: 0 UID: 0 PID: 59 Comm: kworker/u8:4 Not tainted 6.16.0-rc5-syzkaller-00276-g5d5d62298b8b #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: loop4 loop_workfn
Call Trace:
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x230 mm/kasan/report.c:480
kasan_report+0x118/0x150 mm/kasan/report.c:593
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
put_bh include/linux/buffer_head.h:304 [inline]
end_buffer_read_sync+0xc3/0xe0 fs/buffer.c:161
end_bio_bh_io_sync+0xbd/0x120 fs/buffer.c:2783
blk_update_request+0x5eb/0xe70 block/blk-mq.c:987
blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1149
blk_complete_reqs block/blk-mq.c:1224 [inline]
blk_done_softirq+0x10a/0x160 block/blk-mq.c:1229
handle_softirqs+0x286/0x870 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_call_function_single arch/x86/kernel/smp.c:266 [inline]
sysvec_call_function_single+0xa3/0xc0 arch/x86/kernel/smp.c:266
asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:709
RIP: 0010:raise_softirq+0xcc/0x120 kernel/softirq.c:741
Code: fd 41 00 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 49 41 f7 c4 00 02 00 00 74 01 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 3e 00 00 00 00 66 43 c7 44 3e 09 00 00 43 c6 44 3e 0b 00
RSP: 0018:ffffc9000210f400 EFLAGS: 00000206
RAX: 67e835128c507800 RBX: 0000000000000004 RCX: 67e835128c507800
RDX: 0000000000000006 RSI: ffffffff8d998d6f RDI: ffffffff8be29d80
RBP: ffffc9000210f4b0 R08: ffffffff8fa1f5f7 R09: 1ffffffff1f43ebe
R10: dffffc0000000000 R11: fffffbfff1f43ebf R12: 0000000000000212
R13: 1ffff92000421e9c R14: 1ffff92000421e80 R15: dffffc0000000000
blk_mq_raise_softirq block/blk-mq.c:1286 [inline]
blk_mq_complete_request_remote+0x6f7/0xa50 block/blk-mq.c:1310
blk_mq_complete_request+0x19/0xa0 block/blk-mq.c:1326
lo_rw_aio_complete drivers/block/loop.c:328 [inline]
lo_rw_aio+0xe0b/0x1040 drivers/block/loop.c:402
do_req_filebacked drivers/block/loop.c:-1 [inline]
loop_handle_cmd drivers/block/loop.c:1889 [inline]
loop_process_work+0x810/0xf40 drivers/block/loop.c:1924
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
The buggy address ffffc900048ef700 belongs to a vmalloc virtual mapping
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x80331
memcg:ffff8880326fc982
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff8880326fc982
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 49, tgid 49 (kworker/u8:3), ts 192248198251, free_ts 192190003014
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
alloc_frozen_pages_noprof mm/mempolicy.c:2490 [inline]
alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2510
vm_area_alloc_pages mm/vmalloc.c:3642 [inline]
__vmalloc_area_node mm/vmalloc.c:3720 [inline]
__vmalloc_node_range_noprof+0x97d/0x12f0 mm/vmalloc.c:3893
__vmalloc_node_noprof+0xc2/0x110 mm/vmalloc.c:3956
alloc_thread_stack_node kernel/fork.c:317 [inline]
dup_task_struct+0x3e7/0x860 kernel/fork.c:877
copy_process+0x544/0x3b80 kernel/fork.c:1999
kernel_clone+0x21e/0x870 kernel/fork.c:2599
user_mode_thread+0xdd/0x140 kernel/fork.c:2677
call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
call_usermodehelper_exec_work+0x9c/0x230 kernel/umh.c:163
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
page last free pid 5840 tgid 5840 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
vfree+0x25a/0x400 mm/vmalloc.c:3434
bch2_fs_btree_write_buffer_exit+0x1ac/0x1e0 fs/bcachefs/btree_write_buffer.c:871
__bch2_fs_free fs/bcachefs/super.c:615 [inline]
bch2_fs_release+0x297/0x830 fs/bcachefs/super.c:667
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x22b/0x480 lib/kobject.c:737
deactivate_locked_super+0xbc/0x130 fs/super.c:474
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1417
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:114
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffffc900048ef600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc900048ef680: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
>ffffc900048ef700: 00 00 00 00 00 00 00 f2 f2 f2 f2 f2 00 f2 f2 f2
^
ffffc900048ef780: 01 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
ffffc900048ef800: 00 00 00 00 f1 f1 f1 f1 00 f3 f3 f3 00 00 00 00
==================================================================
vkms_vblank_simulate: vblank timer overrun
----------------
Code disassembly (best guess):
0: fd std
1: 41 00 48 c7 add %cl,-0x39(%r8)
5: 44 24 20 rex.R and $0x20,%al
8: 00 00 add %al,(%rax)
a: 00 00 add %al,(%rax)
c: 9c pushf
d: 8f 44 24 20 pop 0x20(%rsp)
11: f6 44 24 21 02 testb $0x2,0x21(%rsp)
16: 75 49 jne 0x61
18: 41 f7 c4 00 02 00 00 test $0x200,%r12d
1f: 74 01 je 0x22
21: fb sti
22: 48 c7 04 24 0e 36 e0 movq $0x45e0360e,(%rsp)
29: 45
* 2a: 4b c7 04 3e 00 00 00 movq $0x0,(%r14,%r15,1) <-- trapping instruction
31: 00
32: 66 43 c7 44 3e 09 00 movw $0x0,0x9(%r14,%r15,1)
39: 00
3a: 43 c6 44 3e 0b 00 movb $0x0,0xb(%r14,%r15,1)