==================================================================
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 ffffc9000405f700 by task kworker/u8:6/998

CPU: 1 UID: 0 PID: 998 Comm: kworker/u8:6 Not tainted 6.16.0-rc4-syzkaller-00013-g66701750d556 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <IRQ>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 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+0x107/0x160 block/blk-mq.c:1229
 handle_softirqs+0x283/0x870 kernel/softirq.c:579
 do_softirq+0xec/0x180 kernel/softirq.c:480
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:407
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 batadv_nc_purge_paths+0x318/0x3b0 net/batman-adv/network-coding.c:471
 batadv_nc_worker+0x328/0x610 net/batman-adv/network-coding.c:720
 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
 </TASK>

The buggy address belongs to the virtual mapping at
 [ffffc90004058000, ffffc90004061000) created by:
 copy_process+0x54b/0x3c00 kernel/fork.c:1999

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x22b9b
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 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 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 6526, tgid 6526 (dhcpcd-run-hook), ts 134852190839, free_ts 131291163718
 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+0x21d5/0x22b0 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:3634 [inline]
 __vmalloc_area_node mm/vmalloc.c:3712 [inline]
 __vmalloc_node_range_noprof+0x97d/0x12f0 mm/vmalloc.c:3885
 __vmalloc_node_noprof+0xc2/0x110 mm/vmalloc.c:3948
 alloc_thread_stack_node kernel/fork.c:317 [inline]
 dup_task_struct+0x3e7/0x860 kernel/fork.c:877
 copy_process+0x54b/0x3c00 kernel/fork.c:1999
 kernel_clone+0x224/0x7f0 kernel/fork.c:2599
 __do_sys_clone kernel/fork.c:2742 [inline]
 __se_sys_clone kernel/fork.c:2726 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2726
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6467 tgid 6467 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc65/0xe60 mm/page_alloc.c:2706
 discard_slab mm/slub.c:2717 [inline]
 __put_partials+0x161/0x1c0 mm/slub.c:3186
 put_cpu_partial+0x17c/0x250 mm/slub.c:3261
 __slab_free+0x2f7/0x400 mm/slub.c:4513
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4204
 getname_flags+0xb8/0x540 fs/namei.c:146
 do_readlinkat+0xbc/0x500 fs/stat.c:575
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:610
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffffc9000405f600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000405f680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000405f700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                      ^
 ffffc9000405f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc9000405f800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================