================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in atomic_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:705 [inline] BUG: KASAN: use-after-free in queued_spin_lock include/asm-generic/qspinlock.h:82 [inline] BUG: KASAN: use-after-free in do_raw_spin_lock_flags include/linux/spinlock.h:196 [inline] BUG: KASAN: use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [inline] BUG: KASAN: use-after-free in _raw_spin_lock_irqsave+0xb5/0x130 kernel/locking/spinlock.c:159 Write of size 4 at addr ffff88812268e038 by task f2fs_discard-7:/2697 CPU: 1 PID: 2697 Comm: f2fs_discard-7: Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_try_cmpxchg_acquire include/asm-generic/atomic-instrumented.h:705 [inline] queued_spin_lock include/asm-generic/qspinlock.h:82 [inline] do_raw_spin_lock_flags include/linux/spinlock.h:196 [inline] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irqsave+0xb5/0x130 kernel/locking/spinlock.c:159 prepare_to_wait_event+0x2a/0x410 kernel/sched/wait.c:296 issue_discard_thread+0x7a9/0x1360 fs/f2fs/segment.c:1815 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Allocated by task 4354: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:430 [inline] __kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:463 kasan_slab_alloc include/linux/kasan.h:244 [inline] slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580 slab_alloc_node mm/slub.c:2952 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc+0x162/0x2d0 mm/slub.c:2965 kmem_cache_alloc_node include/linux/slab.h:426 [inline] __alloc_skb+0x9e/0x520 net/core/skbuff.c:200 alloc_skb include/linux/skbuff.h:1126 [inline] alloc_skb_with_frags+0xa2/0x560 net/core/skbuff.c:5993 sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2393 unix_dgram_sendmsg+0x601/0x17e0 net/unix/af_unix.c:1725 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2376 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2430 __sys_sendmmsg+0x2ab/0x4c0 net/socket.c:2516 __do_sys_sendmmsg net/socket.c:2545 [inline] __se_sys_sendmmsg net/socket.c:2542 [inline] __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2542 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Freed by task 4353: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370 kasan_slab_free include/linux/kasan.h:220 [inline] slab_free_hook mm/slub.c:1600 [inline] slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626 slab_free mm/slub.c:3208 [inline] kmem_cache_free+0x100/0x2d0 mm/slub.c:3224 kfree_skbmem+0x10c/0x180 net/core/skbuff.c:-1 __kfree_skb net/core/skbuff.c:695 [inline] kfree_skb+0xc1/0x2f0 net/core/skbuff.c:713 unix_release_sock+0x834/0xae0 net/unix/af_unix.c:563 unix_release+0x4e/0x80 net/unix/af_unix.c:869 __sock_release net/socket.c:597 [inline] sock_close+0xe0/0x270 net/socket.c:1286 __fput+0x2fb/0x770 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb The buggy address belongs to the object at ffff88812268e000 which belongs to the cache skbuff_head_cache of size 248 The buggy address is located 56 bytes inside of 248-byte region [ffff88812268e000, ffff88812268e0f8) The buggy address belongs to the page: page:ffffea000489a380 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12268e flags: 0x4000000000000200(slab) raw: 4000000000000200 0000000000000000 0000000200000001 ffff888107d92480 raw: 0000000000000000 00000000000c000c 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 94, ts 166684358977, free_ts 166681933372 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5384 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1813 [inline] new_slab+0x84/0x3f0 mm/slub.c:1874 new_slab_objects mm/slub.c:2632 [inline] ___slab_alloc+0x2a6/0x450 mm/slub.c:2796 __slab_alloc+0x63/0xa0 mm/slub.c:2836 slab_alloc_node mm/slub.c:2918 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc+0x1ac/0x2d0 mm/slub.c:2965 kmem_cache_alloc_node include/linux/slab.h:426 [inline] __alloc_skb+0x9e/0x520 net/core/skbuff.c:200 alloc_skb include/linux/skbuff.h:1126 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1178 [inline] netlink_sendmsg+0x605/0xb50 net/netlink/af_netlink.c:1889 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2376 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2430 __sys_sendmsg net/socket.c:2459 [inline] __do_sys_sendmsg net/socket.c:2468 [inline] __se_sys_sendmsg net/socket.c:2466 [inline] __x64_sys_sendmsg+0x1f9/0x2c0 net/socket.c:2466 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] free_pcp_prepare mm/page_alloc.c:1421 [inline] free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336 free_unref_page_list+0x129/0x9c0 mm/page_alloc.c:3443 release_pages+0xe52/0xea0 mm/swap.c:1103 __pagevec_release+0x71/0xe0 mm/swap.c:1123 pagevec_release include/linux/pagevec.h:88 [inline] truncate_inode_pages_range+0x819/0x16d0 mm/truncate.c:367 truncate_inode_pages mm/truncate.c:473 [inline] truncate_inode_pages_final+0xc0/0xd0 mm/truncate.c:524 ext4_evict_inode+0x640/0x1770 fs/ext4/inode.c:214 evict+0x4ae/0x930 fs/inode.c:612 iput_final fs/inode.c:1736 [inline] iput+0x638/0x7c0 fs/inode.c:1762 ext4_mb_release+0x68f/0xbf0 fs/ext4/mballoc.c:3114 ext4_put_super+0x1cd/0x9c0 fs/ext4/super.c:1195 generic_shutdown_super+0x149/0x320 fs/super.c:465 kill_block_super+0x7f/0xf0 fs/super.c:1469 deactivate_locked_super+0xa0/0x100 fs/super.c:335 deactivate_super+0xaf/0xe0 fs/super.c:366 cleanup_mnt+0x45b/0x510 fs/namespace.c:1123 Memory state around the buggy address: ffff88812268df00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88812268df80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88812268e000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88812268e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc ffff88812268e100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ================================================================== list_del corruption. prev->next should be ffffc90001e87e58, but was 0000000000000086 ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:61! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 2697 Comm: f2fs_discard-7: Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:__list_del_entry_valid+0x10c/0x120 lib/list_debug.c:59 Code: 48 89 de e8 a6 a2 38 02 0f 0b 48 c7 c7 60 86 40 85 48 89 de e8 95 a2 38 02 0f 0b 48 c7 c7 c0 86 40 85 48 89 de e8 84 a2 38 02 <0f> 0b 48 c7 c7 20 87 40 85 48 89 de e8 73 a2 38 02 0f 0b 00 55 48 RSP: 0018:ffffc90001e87c80 EFLAGS: 00010046 RAX: 0000000000000054 RBX: ffffc90001e87e58 RCX: 5e92fd21aee50300 RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000 RBP: ffffc90001e87ca0 R08: ffff8881f7152fbf R09: 1ffff1103ee2a5f7 R10: dffffc0000000000 R11: ffffed103ee2a5f8 R12: dffffc0000000000 R13: ffff88812268e038 R14: ffff88812268e040 R15: ffff88812268e040 FS: 0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f45cc5238b0 CR3: 000000010cd4e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __list_del_entry include/linux/list.h:132 [inline] list_del_init include/linux/list.h:204 [inline] finish_wait+0xb0/0x190 kernel/sched/wait.c:397 issue_discard_thread+0x8a3/0x1360 fs/f2fs/segment.c:1815 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Modules linked in: ---[ end trace 14eec8ee4aa7f67f ]--- RIP: 0010:__list_del_entry_valid+0x10c/0x120 lib/list_debug.c:59 Code: 48 89 de e8 a6 a2 38 02 0f 0b 48 c7 c7 60 86 40 85 48 89 de e8 95 a2 38 02 0f 0b 48 c7 c7 c0 86 40 85 48 89 de e8 84 a2 38 02 <0f> 0b 48 c7 c7 20 87 40 85 48 89 de e8 73 a2 38 02 0f 0b 00 55 48 RSP: 0018:ffffc90001e87c80 EFLAGS: 00010046 RAX: 0000000000000054 RBX: ffffc90001e87e58 RCX: 5e92fd21aee50300 RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000 RBP: ffffc90001e87ca0 R08: ffff8881f7152fbf R09: 1ffff1103ee2a5f7 R10: dffffc0000000000 R11: ffffed103ee2a5f8 R12: dffffc0000000000 R13: ffff88812268e038 R14: ffff88812268e040 R15: ffff88812268e040 FS: 0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f45cc5238b0 CR3: 000000010cd4e000 CR4: 00000000003506a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400