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BUG: KASAN: out-of-bounds in instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
BUG: KASAN: out-of-bounds in atomic_dec include/linux/atomic/atomic-instrumented.h:257 [inline]
BUG: KASAN: out-of-bounds in put_bh include/linux/buffer_head.h:320 [inline]
BUG: KASAN: out-of-bounds in end_buffer_read_sync+0xe4/0x190 fs/buffer.c:160
Write of size 4 at addr ffff800021fb7580 by task ksoftirqd/0/15

CPU: 0 PID: 15 Comm: ksoftirqd/0 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/18/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 print_address_description+0x88/0x200 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:418
 kasan_report+0xa8/0x100 mm/kasan/report.c:522
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x260/0x2a0 mm/kasan/generic.c:189
 __kasan_check_write+0x2c/0x3c mm/kasan/shadow.c:37
 instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
 atomic_dec include/linux/atomic/atomic-instrumented.h:257 [inline]
 put_bh include/linux/buffer_head.h:320 [inline]
 end_buffer_read_sync+0xe4/0x190 fs/buffer.c:160
 end_bio_bh_io_sync+0xb0/0x1e0 fs/buffer.c:2655
 bio_endio+0x770/0x7b4 block/bio.c:1554
 req_bio_endio block/blk-mq.c:780 [inline]
 blk_update_request+0x49c/0xbec block/blk-mq.c:925
 blk_mq_end_request+0x54/0x88 block/blk-mq.c:1050
 lo_complete_rq+0x1ec/0x250 drivers/block/loop.c:365
 blk_complete_reqs block/blk-mq.c:1130 [inline]
 blk_done_softirq+0x11c/0x168 block/blk-mq.c:1135
 handle_softirqs+0x318/0xc6c kernel/softirq.c:596
 run_ksoftirqd+0x7c/0x2a0 kernel/softirq.c:963
 smpboot_thread_fn+0x4b0/0x964 kernel/smpboot.c:164
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849

The buggy address ffff800021fb7580 belongs to a vmalloc virtual mapping
The buggy address belongs to the physical page:
page:0000000041cddadf refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1320f8
memcg:ffff0000ea3abd02
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff0000ea3abd02
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff800021fb7480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff800021fb7500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff800021fb7580: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
                      ^
 ffff800021fb7600: 00 00 00 f2 f2 f2 f2 f2 00 f3 f3 f3 00 00 00 00
 ffff800021fb7680: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
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