EXT4-fs (loop2): 1 truncate cleaned up EXT4-fs (loop2): mounted filesystem without journal. Opts: noblock_validity,max_batch_time=0x0000000000000002,resuid=0x0000000000000000,block_validity,stripe=0x0000000000000009,nombcache,,errors=continue. Quota mode: none. ================================================================== BUG: KASAN: use-after-free in ext4_search_dir+0xf8/0x1c0 fs/ext4/namei.c:1544 Read of size 1 at addr ffff888111663c86 by task syz.2.18/377 CPU: 0 PID: 377 Comm: syz.2.18 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report+0x10f/0x150 mm/kasan/report.c:444 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306 ext4_search_dir+0xf8/0x1c0 fs/ext4/namei.c:1544 ext4_find_inline_entry+0x4f2/0x630 fs/ext4/inline.c:1748 __ext4_find_entry+0x307/0x1a10 fs/ext4/namei.c:1617 ext4_lookup_entry fs/ext4/namei.c:1774 [inline] ext4_lookup+0x382/0x930 fs/ext4/namei.c:1842 lookup_one_qstr_excl+0x114/0x250 fs/namei.c:1571 filename_create+0x23d/0x440 fs/namei.c:3844 do_mkdirat+0x5c/0x4d0 fs/namei.c:4088 __do_sys_mkdirat fs/namei.c:4113 [inline] __se_sys_mkdirat fs/namei.c:4111 [inline] __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4111 x64_sys_call+0x37e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fc2384a2cc7 Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff17604298 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fff17604320 RCX: 00007fc2384a2cc7 RDX: 00000000000001ff RSI: 0000200000000080 RDI: 00000000ffffff9c RBP: 0000200000000140 R08: 0000200000000080 R09: 0000000000000000 R10: 0000200000000140 R11: 0000000000000246 R12: 0000200000000080 R13: 00007fff176042e0 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 115: 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:433 [inline] __kasan_slab_alloc+0xb7/0xe0 mm/kasan/common.c:466 kasan_slab_alloc include/linux/kasan.h:217 [inline] slab_post_alloc_hook+0x4f/0x2b0 mm/slab.h:550 slab_alloc_node mm/slub.c:3245 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc+0xf7/0x260 mm/slub.c:3260 kmem_cache_alloc_node include/linux/slab.h:492 [inline] __alloc_skb+0xe4/0x730 net/core/skbuff.c:416 alloc_skb include/linux/skbuff.h:1183 [inline] alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x335/0x5a0 lib/kobject_uevent.c:409 kobject_uevent_env+0x52b/0x700 lib/kobject_uevent.c:608 kobject_synth_uevent+0x457/0x940 lib/kobject_uevent.c:208 uevent_store+0x25/0x60 drivers/base/core.c:2438 dev_attr_store+0x5e/0x80 drivers/base/core.c:2136 sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:139 kernfs_fop_write_iter+0x2bd/0x400 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2212 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x831/0xfd0 fs/read_write.c:594 ksys_write+0x14a/0x260 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:656 x64_sys_call+0x8ef/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 The buggy address belongs to the object at ffff888111663c80 which belongs to the cache skbuff_head_cache of size 248 The buggy address is located 6 bytes inside of 248-byte region [ffff888111663c80, ffff888111663d78) The buggy address belongs to the page: page:ffffea00044598c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888111663b40 pfn:0x111663 flags: 0x4000000000000200(slab|zone=1) raw: 4000000000000200 ffff88810014a110 ffffea0004459908 ffff8881081ab980 raw: ffff888111663b40 00000000000c0006 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 115, ts 4121907690, free_ts 0 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4485 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5822 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1937 [inline] new_slab+0xa0/0x4d0 mm/slub.c:2000 ___slab_alloc+0x3ac/0x840 mm/slub.c:3033 __slab_alloc+0x49/0x90 mm/slub.c:3120 slab_alloc_node mm/slub.c:3211 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc+0x138/0x260 mm/slub.c:3260 kmem_cache_alloc_node include/linux/slab.h:492 [inline] __alloc_skb+0xe4/0x730 net/core/skbuff.c:416 alloc_skb include/linux/skbuff.h:1183 [inline] alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x335/0x5a0 lib/kobject_uevent.c:409 kobject_uevent_env+0x52b/0x700 lib/kobject_uevent.c:608 kobject_synth_uevent+0x457/0x940 lib/kobject_uevent.c:208 uevent_store+0x25/0x60 drivers/base/core.c:2438 dev_attr_store+0x5e/0x80 drivers/base/core.c:2136 sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:139 page_owner free stack trace missing Memory state around the buggy address: ffff888111663b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888111663c00: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc >ffff888111663c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888111663d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc ffff888111663d80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ================================================================== EXT4-fs error (device loop2): ext4_check_all_de:667: inode #12: block 7: comm syz.2.18: bad entry in directory: directory entry overrun - offset=0, inode=901261600, rec_len=7976, size=124 fake=0