================================================================== BUG: KASAN: use-after-free in ext4_htree_fill_tree+0x1080/0x10e0 fs/ext4/namei.c:1221 Read of size 1 at addr ffff888116eabf7a by task syz-executor/1092 CPU: 1 PID: 1092 Comm: syz-executor Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 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+0x100/0x140 mm/kasan/report.c:452 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306 ext4_htree_fill_tree+0x1080/0x10e0 fs/ext4/namei.c:1221 ext4_dx_readdir fs/ext4/dir.c:601 [inline] ext4_readdir+0x2bcf/0x3a80 fs/ext4/dir.c:145 iterate_dir+0x25c/0x560 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 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f01ad7d4a73 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:00007ffd0df79728 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 0000555564529910 RCX: 00007f01ad7d4a73 RDX: 0000000000008000 RSI: 0000555564529940 RDI: 0000000000000005 RBP: 0000555564529940 R08: 00007f01ada00e20 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000293 R12: 0000555564529914 R13: ffffffffffffffe8 R14: 0000000000000010 R15: 00007ffd0df7b9d0 The buggy address belongs to the page: page:ffffea00045baac0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x116eab flags: 0x4000000000000000() raw: 4000000000000000 ffffea0004be3108 ffffea00045baa88 0000000000000000 raw: 0000000000000000 00000000000c0000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 1206, ts 56506086139, free_ts 71481861243 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x176/0x190 mm/page_alloc.c:2462 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x29a/0x640 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+0x2f8/0x4c0 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+0x1a4/0x2d0 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] nlmsg_new include/net/netlink.h:953 [inline] rtmsg_fib+0x5fe/0xd90 net/ipv4/fib_semantics.c:520 fib_table_insert+0xee3/0x1d50 net/ipv4/fib_trie.c:1335 fib_magic net/ipv4/fib_frontend.c:1107 [inline] fib_add_ifaddr+0xbe3/0xf90 net/ipv4/fib_frontend.c:1153 fib_netdev_event+0x22e/0x5b0 net/ipv4/fib_frontend.c:1491 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410 call_netdevice_notifiers_info net/core/dev.c:2052 [inline] call_netdevice_notifiers_extack net/core/dev.c:2064 [inline] call_netdevice_notifiers net/core/dev.c:2078 [inline] __dev_notify_flags+0x2f4/0x5b0 net/core/dev.c:8583 dev_change_flags+0xe3/0x1a0 net/core/dev.c:8621 do_setlink+0xb19/0x29a0 net/core/rtnetlink.c:2744 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 mm/page_alloc.c:3391 [inline] free_the_page mm/page_alloc.c:5443 [inline] __free_pages+0x146/0x390 mm/page_alloc.c:5454 __free_slab+0xcf/0x190 mm/slub.c:1899 free_slab mm/slub.c:1914 [inline] discard_slab mm/slub.c:1920 [inline] unfreeze_partials+0x150/0x180 mm/slub.c:2415 put_cpu_partial+0xc1/0x180 mm/slub.c:2451 __slab_free+0x2c9/0x3a0 mm/slub.c:3100 do_slab_free mm/slub.c:3196 [inline] ___cache_free+0x10e/0x130 mm/slub.c:3215 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440 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+0x15a/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+0x693/0xb70 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2377 Memory state around the buggy address: ffff888116eabe00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888116eabe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff888116eabf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888116eabf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888116eac000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== EXT4-fs error (device loop2): htree_dirblock_to_tree:1092: inode #2: block 33: comm syz-executor: bad entry in directory: rec_len is smaller than minimal - offset=1024, inode=0, rec_len=0, size=1024 fake=0