EXT4-fs error (device loop0): ext4_readdir:263: inode #12: block 80: comm syz-executor: path /6/file1/file0: bad entry in directory: rec_len is smaller than minimal - offset=12, inode=6, rec_len=0, size=4096 fake=0 ================================================================== BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:930 [inline] BUG: KASAN: use-after-free in enqueue_timer+0xae/0x480 kernel/time/timer.c:611 Write of size 8 at addr ffff8881136c24c0 by task syz-executor/289 CPU: 0 PID: 289 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x71/0x200 mm/kasan/report.c:316 print_report+0x4a/0x60 mm/kasan/report.c:420 kasan_report+0x122/0x150 mm/kasan/report.c:524 __asan_report_store8_noabort+0x17/0x20 mm/kasan/report_generic.c:356 hlist_add_head include/linux/list.h:930 [inline] enqueue_timer+0xae/0x480 kernel/time/timer.c:611 internal_add_timer kernel/time/timer.c:640 [inline] __mod_timer+0x84c/0xc00 kernel/time/timer.c:1137 mod_timer+0x1f/0x30 kernel/time/timer.c:1196 ext4_update_super+0xa54/0xe40 fs/ext4/super.c:6089 ext4_commit_super+0xe3/0x4b0 fs/ext4/super.c:6108 ext4_handle_error+0x5c8/0x860 fs/ext4/super.c:678 __ext4_error_file+0x34d/0x640 fs/ext4/super.c:851 __ext4_check_dir_entry+0x763/0x970 fs/ext4/dir.c:114 ext4_readdir+0x1315/0x3e10 fs/ext4/dir.c:261 iterate_dir+0x271/0x610 fs/readdir.c:-1 __do_sys_getdents64 fs/readdir.c:369 [inline] __se_sys_getdents64+0xf2/0x250 fs/readdir.c:354 __x64_sys_getdents64+0x7b/0x90 fs/readdir.c:354 x64_sys_call+0x15c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:218 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fa45c5c5773 Code: c7 c0 e8 ff ff ff 64 c7 00 16 00 00 00 31 c0 eb 9e e8 81 9b fd ff 90 b8 ff ff ff 7f 48 39 c2 48 0f 47 d0 b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 c7 c2 e8 ff ff ff f7 d8 RSP: 002b:00007ffef2032078 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 000055557953f950 RCX: 00007fa45c5c5773 RDX: 0000000000008000 RSI: 000055557953f980 RDI: 0000000000000006 RBP: 000055557953f980 R08: 00007fa45c7ede20 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000293 R12: 000055557953f954 R13: ffffffffffffffe8 R14: 0000000000000016 R15: 00007ffef2035410 Allocated by task 318: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:380 [inline] __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389 kasan_kmalloc include/linux/kasan.h:212 [inline] kmalloc_trace+0x40/0xb0 mm/slab_common.c:1033 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] ext4_alloc_sbi fs/ext4/super.c:4258 [inline] ext4_fill_super+0x11d/0x7590 fs/ext4/super.c:5661 get_tree_bdev+0x447/0x690 fs/super.c:1371 ext4_get_tree+0x1c/0x20 fs/ext4/super.c:5704 vfs_get_tree+0x9a/0x270 fs/super.c:1578 do_new_mount+0x251/0xb30 fs/namespace.c:3081 path_mount+0x659/0xfc0 fs/namespace.c:3411 do_mount fs/namespace.c:3424 [inline] __do_sys_mount fs/namespace.c:3632 [inline] __se_sys_mount+0x320/0x390 fs/namespace.c:3609 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3609 x64_sys_call+0x65d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Freed by task 291: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250 kasan_slab_free include/linux/kasan.h:178 [inline] slab_free_hook mm/slub.c:1750 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776 slab_free mm/slub.c:3712 [inline] __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728 kfree+0x6f/0xf0 mm/slab_common.c:990 ext4_put_super+0x9b6/0xac0 fs/ext4/super.c:1313 generic_shutdown_super+0x16c/0x480 fs/super.c:506 kill_block_super+0x7f/0xf0 fs/super.c:1475 deactivate_locked_super+0xb5/0x120 fs/super.c:336 deactivate_super+0xaf/0xe0 fs/super.c:367 cleanup_mnt+0x474/0x500 fs/namespace.c:1192 __cleanup_mnt+0x19/0x20 fs/namespace.c:1199 task_work_run+0x1e1/0x250 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0xa35/0x2660 kernel/exit.c:886 do_group_exit+0x210/0x2d0 kernel/exit.c:1028 __do_sys_exit_group kernel/exit.c:1039 [inline] __se_sys_exit_group kernel/exit.c:1037 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1037 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 The buggy address belongs to the object at ffff8881136c2000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 1216 bytes inside of 4096-byte region [ffff8881136c2000, ffff8881136c3000) The buggy address belongs to the physical page: page:ffffea00044db000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1136c0 head:ffffea00044db000 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 dead000000000001 ffff888100043380 raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 117, tgid 117 (udevadm), ts 4990115814, free_ts 0 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672 prep_new_page+0x1c/0x110 mm/page_alloc.c:2679 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4585 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5926 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1 allocate_slab mm/slub.c:1967 [inline] new_slab+0x98/0x3d0 mm/slub.c:2020 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3177 __slab_alloc+0x5e/0xa0 mm/slub.c:3263 slab_alloc_node mm/slub.c:3348 [inline] __kmem_cache_alloc_node+0x203/0x2c0 mm/slub.c:3423 kmalloc_trace+0x29/0xb0 mm/slab_common.c:1028 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] kernfs_iop_get_link+0x65/0x620 fs/kernfs/symlink.c:135 vfs_readlink+0x18f/0x410 fs/namei.c:5130 do_readlinkat+0x251/0x490 fs/stat.c:480 __do_sys_readlink fs/stat.c:501 [inline] __se_sys_readlink fs/stat.c:498 [inline] __x64_sys_readlink+0x7f/0x90 fs/stat.c:498 x64_sys_call+0x87f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:90 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 page_owner free stack trace missing Memory state around the buggy address: ffff8881136c2380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881136c2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881136c2480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881136c2500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881136c2580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== EXT4-fs (loop0): unmounting filesystem.