================================================================== BUG: KASAN: use-after-free in ext4_htree_fill_tree+0x1066/0x10d0 fs/ext4/namei.c:1246 Read of size 1 at addr ffff88811d857535 by task syz-executor/479 CPU: 0 PID: 479 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:88 dump_stack_lvl+0xee/0x150 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_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:348 ext4_htree_fill_tree+0x1066/0x10d0 fs/ext4/namei.c:1246 ext4_dx_readdir fs/ext4/dir.c:608 [inline] ext4_readdir+0x2d8a/0x3c10 fs/ext4/dir.c:145 iterate_dir+0x271/0x610 fs/readdir.c:-1 __do_sys_getdents64 fs/readdir.c:369 [inline] __se_sys_getdents64+0xe5/0x240 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:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f3ef49bfad3 Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 72 3e f8 ff 66 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 a8 ff ff ff f7 d8 RSP: 002b:00007ffd9a406f68 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 0000555560ddb4e0 RCX: 00007f3ef49bfad3 RDX: 0000000000008000 RSI: 0000555560ddb4e0 RDI: 0000000000000005 RBP: 0000555560ddb4b4 R08: 0000000000028b61 R09: 0000000000000000 R10: 00007f3ef4b7cca0 R11: 0000000000000293 R12: ffffffffffffffa8 R13: 0000000000000010 R14: 0000555560ddb4b0 R15: 00007ffd9a409220 Allocated by task 141: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:333 kasan_slab_alloc include/linux/kasan.h:202 [inline] slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768 slab_alloc_node mm/slub.c:3382 [inline] kmem_cache_alloc_node+0x181/0x340 mm/slub.c:3429 __alloc_skb+0xea/0x4b0 net/core/skbuff.c:508 alloc_skb include/linux/skbuff.h:1290 [inline] alloc_skb_with_frags+0xa8/0x620 net/core/skbuff.c:6165 sock_alloc_send_pskb+0x853/0x980 net/core/sock.c:2756 unix_dgram_sendmsg+0x592/0x16d0 net/unix/af_unix.c:1947 unix_seqpacket_sendmsg+0x118/0x1e0 net/unix/af_unix.c:2408 sock_sendmsg_nosec net/socket.c:716 [inline] __sock_sendmsg net/socket.c:728 [inline] sock_write_iter+0x2ca/0x3b0 net/socket.c:1133 do_iter_readv_writev fs/read_write.c:-1 [inline] do_iter_write+0x650/0xb10 fs/read_write.c:861 vfs_writev+0x30b/0x590 fs/read_write.c:934 do_writev+0x14a/0x2b0 fs/read_write.c:977 __do_sys_writev fs/read_write.c:1050 [inline] __se_sys_writev fs/read_write.c:1047 [inline] __x64_sys_writev+0x7d/0x90 fs/read_write.c:1047 x64_sys_call+0xad/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:21 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 The buggy address belongs to the object at ffff88811d857500 which belongs to the cache skbuff_head_cache of size 256 The buggy address is located 53 bytes inside of 256-byte region [ffff88811d857500, ffff88811d857600) The buggy address belongs to the physical page: page:ffffea00047615c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88811d8578c0 pfn:0x11d857 flags: 0x4000000000000200(slab|zone=1) raw: 4000000000000200 ffffea0004760540 dead000000000003 ffff888108c5d500 raw: ffff88811d8578c0 00000000800c0000 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 141, tgid 141 (dhcpcd), ts 6784490267, free_ts 0 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+0x2c7b/0x2cf0 mm/page_alloc.c:4554 __alloc_pages+0x1c3/0x450 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+0x1c2/0x340 mm/slub.c:3429 __alloc_skb+0xea/0x4b0 net/core/skbuff.c:508 alloc_skb include/linux/skbuff.h:1290 [inline] alloc_skb_with_frags+0xa8/0x620 net/core/skbuff.c:6165 sock_alloc_send_pskb+0x853/0x980 net/core/sock.c:2756 unix_dgram_sendmsg+0x592/0x16d0 net/unix/af_unix.c:1947 unix_seqpacket_sendmsg+0x118/0x1e0 net/unix/af_unix.c:2408 sock_sendmsg_nosec net/socket.c:716 [inline] __sock_sendmsg net/socket.c:728 [inline] sock_write_iter+0x2ca/0x3b0 net/socket.c:1133 do_iter_readv_writev fs/read_write.c:-1 [inline] do_iter_write+0x650/0xb10 fs/read_write.c:861 page_owner free stack trace missing Memory state around the buggy address: ffff88811d857400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811d857480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff88811d857500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88811d857580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811d857600: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ================================================================== EXT4-fs (loop3): unmounting filesystem.