EXT4-fs warning (device loop2): dx_probe:833: inode #2: comm syz.2.17: Unrecognised inode hash code 20 EXT4-fs warning (device loop2): dx_probe:966: inode #2: comm syz.2.17: Corrupt directory, running e2fsck is recommended ================================================================== BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x7c2/0x970 fs/ext4/dir.c:85 Read of size 2 at addr ffff888122cb0003 by task syz.2.17/375 CPU: 1 PID: 375 Comm: syz.2.17 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 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_load2_noabort+0x14/0x20 mm/kasan/report_generic.c:349 __ext4_check_dir_entry+0x7c2/0x970 fs/ext4/dir.c:85 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: 0033:0x7f109679aeb9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007ffeabe64878 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007f1096a15fa0 RCX: 00007f109679aeb9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006 RBP: 00007f1096808c1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1096a15fac R14: 00007f1096a15fa0 R15: 00007f1096a15fa0 Allocated by task 295: 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] __do_kmalloc_node mm/slab_common.c:938 [inline] __kmalloc_node_track_caller+0xb1/0x1e0 mm/slab_common.c:958 kmalloc_reserve net/core/skbuff.c:449 [inline] __alloc_skb+0x236/0x4b0 net/core/skbuff.c:518 alloc_skb include/linux/skbuff.h:1290 [inline] alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290 uevent_net_broadcast_tagged lib/kobject_uevent.c:351 [inline] kobject_uevent_net_broadcast+0x1b4/0x5b0 lib/kobject_uevent.c:412 kobject_uevent_env+0x54f/0x730 lib/kobject_uevent.c:608 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 rx_queue_add_kobject net/core/net-sysfs.c:1068 [inline] net_rx_queue_update_kobjects+0x249/0x4d0 net/core/net-sysfs.c:1108 register_queue_kobjects net/core/net-sysfs.c:1768 [inline] netdev_register_kobject+0x26b/0x360 net/core/net-sysfs.c:2013 register_netdevice+0xeb1/0x1530 net/core/dev.c:10168 register_netdev+0x3e/0x50 net/core/dev.c:10294 ip6gre_init_net+0x2b1/0x3b0 net/ipv6/ip6_gre.c:1655 ops_init+0x1c8/0x4a0 net/core/net_namespace.c:138 setup_net+0x4b4/0xcc0 net/core/net_namespace.c:335 copy_net_ns+0x355/0x5c0 net/core/net_namespace.c:481 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:226 ksys_unshare+0x4ba/0x7c0 kernel/fork.c:3415 __do_sys_unshare kernel/fork.c:3486 [inline] __se_sys_unshare kernel/fork.c:3484 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3484 x64_sys_call+0x767/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:273 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 295: 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 skb_free_head net/core/skbuff.c:765 [inline] skb_release_data+0x63f/0x890 net/core/skbuff.c:794 skb_release_all net/core/skbuff.c:859 [inline] __kfree_skb net/core/skbuff.c:873 [inline] consume_skb+0xab/0x1f0 net/core/skbuff.c:1038 netlink_broadcast+0x1084/0x1180 net/netlink/af_netlink.c:1522 uevent_net_broadcast_tagged lib/kobject_uevent.c:372 [inline] kobject_uevent_net_broadcast+0x511/0x5b0 lib/kobject_uevent.c:412 kobject_uevent_env+0x54f/0x730 lib/kobject_uevent.c:608 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 rx_queue_add_kobject net/core/net-sysfs.c:1068 [inline] net_rx_queue_update_kobjects+0x249/0x4d0 net/core/net-sysfs.c:1108 register_queue_kobjects net/core/net-sysfs.c:1768 [inline] netdev_register_kobject+0x26b/0x360 net/core/net-sysfs.c:2013 register_netdevice+0xeb1/0x1530 net/core/dev.c:10168 register_netdev+0x3e/0x50 net/core/dev.c:10294 ip6gre_init_net+0x2b1/0x3b0 net/ipv6/ip6_gre.c:1655 ops_init+0x1c8/0x4a0 net/core/net_namespace.c:138 setup_net+0x4b4/0xcc0 net/core/net_namespace.c:335 copy_net_ns+0x355/0x5c0 net/core/net_namespace.c:481 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:226 ksys_unshare+0x4ba/0x7c0 kernel/fork.c:3415 __do_sys_unshare kernel/fork.c:3486 [inline] __se_sys_unshare kernel/fork.c:3484 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3484 x64_sys_call+0x767/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:273 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 ffff888122cb0000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 3 bytes inside of 1024-byte region [ffff888122cb0000, ffff888122cb0400) The buggy address belongs to the physical page: page:ffffea00048b2c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x122cb0 head:ffffea00048b2c00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 dead000000000122 ffff888100043080 raw: 0000000000000000 0000000000100010 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 295, tgid 295 (syz-executor), ts 28614978480, free_ts 18629284130 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4554 __alloc_pages+0x1d9/0x480 mm/page_alloc.c:5868 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 __do_kmalloc_node mm/slab_common.c:937 [inline] __kmalloc+0xa1/0x1e0 mm/slab_common.c:951 kmalloc include/linux/slab.h:568 [inline] kzalloc include/linux/slab.h:699 [inline] __register_sysctl_table+0xf4/0xe30 fs/proc/proc_sysctl.c:1345 register_net_sysctl+0x24f/0x260 net/sysctl_net.c:169 neigh_sysctl_register+0x9a0/0xa80 net/core/neighbour.c:3852 devinet_sysctl_register+0xaf/0x1e0 net/ipv4/devinet.c:2649 inetdev_init+0x2d1/0x510 net/ipv4/devinet.c:280 inetdev_event+0x1f7/0x10e0 net/ipv4/devinet.c:1547 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1551 [inline] free_pcp_prepare mm/page_alloc.c:1625 [inline] free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3589 free_unref_page+0x95/0x540 mm/page_alloc.c:3687 __folio_put_small mm/swap.c:100 [inline] __folio_put+0xac/0xe0 mm/swap.c:123 folio_put include/linux/mm.h:1442 [inline] put_page include/linux/mm.h:1494 [inline] anon_pipe_buf_release+0x183/0x200 fs/pipe.c:138 pipe_buf_release include/linux/pipe_fs_i.h:199 [inline] pipe_read+0x55b/0x1030 fs/pipe.c:324 call_read_iter include/linux/fs.h:2276 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x454/0x910 fs/read_write.c:470 ksys_read+0x149/0x250 fs/read_write.c:613 __do_sys_read fs/read_write.c:623 [inline] __se_sys_read fs/read_write.c:621 [inline] __x64_sys_read+0x7b/0x90 fs/read_write.c:621 x64_sys_call+0x2f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1 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 Memory state around the buggy address: ffff888122caff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888122caff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888122cb0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888122cb0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888122cb0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== EXT4-fs error (device loop2): ext4_readdir:263: inode #2: block 3: comm syz.2.17: path /0/file0: bad entry in directory: rec_len % 4 != 0 - offset=2047, inode=3703095296, rec_len=33041, size=2048 fake=0 EXT4-fs (loop2): Remounting filesystem read-only