==================================================================
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:308 [inline]
BUG: KASAN: out-of-bounds in end_buffer_read_sync+0xc3/0xd0 fs/buffer.c:161
Write of size 4 at addr ffffc9000450f740 by task kworker/u4:6/1312
CPU: 0 PID: 1312 Comm: kworker/u4:6 Not tainted 6.6.95-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: loop7 loop_workfn
Call Trace:
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x230 mm/kasan/report.c:475
kasan_report+0x117/0x150 mm/kasan/report.c:588
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
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:308 [inline]
end_buffer_read_sync+0xc3/0xd0 fs/buffer.c:161
end_bio_bh_io_sync+0xb7/0x110 fs/buffer.c:2784
req_bio_endio block/blk-mq.c:784 [inline]
blk_update_request+0x597/0xe40 block/blk-mq.c:929
blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1056
blk_complete_reqs block/blk-mq.c:1136 [inline]
blk_done_softirq+0x10b/0x160 block/blk-mq.c:1141
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_call_function_single arch/x86/kernel/smp.c:262 [inline]
sysvec_call_function_single+0xa1/0xc0 arch/x86/kernel/smp.c:262
asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:694
RIP: 0010:raise_softirq+0xfd/0x150 kernel/softirq.c:718
Code: 68 3a 00 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 45 41 f7 c7 00 02 00 00 74 01 fb 48 c7 04 24 0e 36 e0 45 <4a> c7 04 33 00 00 00 00 66 42 c7 44 33 09 00 00 42 c6 44 33 0b 00
RSP: 0018:ffffc90004cff820 EFLAGS: 00000206
RAX: f623d03aa3219900 RBX: 1ffff9200099ff04 RCX: f623d03aa3219900
RDX: dffffc0000000000 RSI: ffffffff8aaab2c0 RDI: ffffffff8afc6ac0
RBP: ffffc90004cff8d0 R08: ffffffff90d85627 R09: 1ffffffff21b0ac4
R10: dffffc0000000000 R11: fffffbfff21b0ac5 R12: 0000000000000004
R13: 1ffff110042e2840 R14: dffffc0000000000 R15: 0000000000000a02
blk_mq_raise_softirq block/blk-mq.c:1197 [inline]
blk_mq_complete_request_remote+0x4e1/0x6c0 block/blk-mq.c:1221
blk_mq_complete_request+0x19/0xa0 block/blk-mq.c:1237
loop_handle_cmd drivers/block/loop.c:1928 [inline]
loop_process_work+0x185b/0x1ed0 drivers/block/loop.c:1946
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
The buggy address belongs to the virtual mapping at
[ffffc90004508000, ffffc90004511000) created by:
copy_process+0x549/0x3d70 kernel/fork.c:2331
The buggy address belongs to the physical page:
page:ffffea00007cf040 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1f3c1
memcg:ffff888060250502
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff888060250502
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 20438, tgid 20438 (syz.7.3251), ts 1809706134496, free_ts 1809165982686
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
vm_area_alloc_pages mm/vmalloc.c:3081 [inline]
__vmalloc_area_node mm/vmalloc.c:3150 [inline]
__vmalloc_node_range+0x96b/0x1320 mm/vmalloc.c:3331
alloc_thread_stack_node kernel/fork.c:310 [inline]
dup_task_struct+0x3d0/0x7c0 kernel/fork.c:1124
copy_process+0x549/0x3d70 kernel/fork.c:2331
kernel_clone+0x21b/0x840 kernel/fork.c:2914
__do_sys_clone3 kernel/fork.c:3215 [inline]
__se_sys_clone3+0x252/0x2c0 kernel/fork.c:3199
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475
release_pages+0x1fa0/0x2220 mm/swap.c:1022
tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
tlb_flush_mmu+0x368/0x4f0 mm/mmu_gather.c:300
tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:392
exit_mmap+0x3f0/0xb50 mm/mmap.c:3311
__mmput+0x118/0x3c0 kernel/fork.c:1355
exit_mm+0x1da/0x2c0 kernel/exit.c:569
do_exit+0x88e/0x23c0 kernel/exit.c:870
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
get_signal+0x12fc/0x1400 kernel/signal.c:2902
arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
Memory state around the buggy address:
ffffc9000450f600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc9000450f680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000450f700: 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 00 00 f2
^
ffffc9000450f780: f2 f2 f2 f2 00 f2 f2 f2 01 f3 f3 f3 00 00 00 00
ffffc9000450f800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
vkms_vblank_simulate: vblank timer overrun
----------------
Code disassembly (best guess):
0: 68 3a 00 48 c7 push $0xffffffffc748003a
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 45 jne 0x5d
18: 41 f7 c7 00 02 00 00 test $0x200,%r15d
1f: 74 01 je 0x22
21: fb sti
22: 48 c7 04 24 0e 36 e0 movq $0x45e0360e,(%rsp)
29: 45
* 2a: 4a c7 04 33 00 00 00 movq $0x0,(%rbx,%r14,1) <-- trapping instruction
31: 00
32: 66 42 c7 44 33 09 00 movw $0x0,0x9(%rbx,%r14,1)
39: 00
3a: 42 c6 44 33 0b 00 movb $0x0,0xb(%rbx,%r14,1)