================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946 Read of size 4 at addr ffff888125c67018 by task syz.2.832/3406 CPU: 0 PID: 3406 Comm: syz.2.832 Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 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+0xf1/0x140 mm/kasan/report.c:444 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 ext4_ext_binsearch fs/ext4/extents.c:827 [inline] ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946 ext4_ext_map_blocks+0x207/0x61e0 fs/ext4/extents.c:4172 ext4_map_blocks+0x988/0x1b30 fs/ext4/inode.c:674 _ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:817 ext4_get_block_unwritten+0x2a/0x40 fs/ext4/inode.c:848 ext4_block_write_begin+0x563/0x1160 fs/ext4/inode.c:1102 ext4_write_begin+0x65a/0x12e0 fs/ext4/ext4_jbd2.h:-1 ext4_da_write_begin+0x321/0xbf0 fs/ext4/inode.c:2988 generic_perform_write+0x2b7/0x690 mm/filemap.c:3870 ext4_buffered_write_iter+0x4ed/0x670 fs/ext4/file.c:270 ext4_file_write_iter+0x440/0x1540 fs/ext4/file.c:-1 call_write_iter include/linux/fs.h:2212 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x835/0xfd0 fs/read_write.c:594 ksys_pwrite64 fs/read_write.c:701 [inline] __do_sys_pwrite64 fs/read_write.c:711 [inline] __se_sys_pwrite64 fs/read_write.c:708 [inline] __x64_sys_pwrite64+0x197/0x220 fs/read_write.c:708 x64_sys_call+0xa6/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:19 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: 0033:0x7f1be1abfdd9 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:00007f1be051a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 RAX: ffffffffffffffda RBX: 00007f1be1d38fa0 RCX: 00007f1be1abfdd9 RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000005 RBP: 00007f1be1b55d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1be1d39038 R14: 00007f1be1d38fa0 R15: 00007ffcc57a28a8 Allocated by task 101: 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+0xbd/0xf0 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+0xe0/0x740 net/core/skbuff.c:416 alloc_skb include/linux/skbuff.h:1183 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1186 [inline] netlink_sendmsg+0x611/0xb80 net/netlink/af_netlink.c:1897 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] ____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2435 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2489 __sys_sendmsg net/socket.c:2518 [inline] __do_sys_sendmsg net/socket.c:2527 [inline] __se_sys_sendmsg net/socket.c:2525 [inline] __x64_sys_sendmsg+0x206/0x2f0 net/socket.c:2525 x64_sys_call+0x4b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47 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 Freed by task 309: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754 slab_free mm/slub.c:3526 [inline] kmem_cache_free+0x100/0x320 mm/slub.c:3544 kfree_skbmem+0x10c/0x180 net/core/skbuff.c:-1 __kfree_skb net/core/skbuff.c:758 [inline] consume_skb+0xb3/0x1f0 net/core/skbuff.c:930 skb_free_datagram+0x28/0xe0 net/core/datagram.c:325 netlink_recvmsg+0x5c6/0xe10 net/netlink/af_netlink.c:2001 ____sys_recvmsg+0x2cd/0x5e0 net/socket.c:-1 ___sys_recvmsg+0x21a/0x5c0 net/socket.c:2696 __sys_recvmsg net/socket.c:2726 [inline] __do_sys_recvmsg net/socket.c:2736 [inline] __se_sys_recvmsg net/socket.c:2733 [inline] __x64_sys_recvmsg+0x203/0x2f0 net/socket.c:2733 x64_sys_call+0x705/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:48 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 ffff888125c67000 which belongs to the cache skbuff_head_cache of size 248 The buggy address is located 24 bytes inside of 248-byte region [ffff888125c67000, ffff888125c670f8) The buggy address belongs to the page: page:ffffea00049719c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x125c67 flags: 0x4000000000000200(slab|zone=1) raw: 4000000000000200 ffffea0004971b40 0000000400000004 ffff8881081ab500 raw: 0000000000000000 00000000000c000c 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 1994, ts 120019419612, free_ts 119296135976 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+0x2d3a/0x2dc0 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+0xa1/0x4d0 mm/slub.c:2000 ___slab_alloc+0x381/0x810 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+0xe0/0x740 net/core/skbuff.c:416 alloc_skb include/linux/skbuff.h:1183 [inline] nlmsg_new include/net/netlink.h:953 [inline] inet6_netconf_notify_devconf+0xd6/0x190 net/ipv6/addrconf.c:585 __addrconf_sysctl_register+0x36e/0x3e0 net/ipv6/addrconf.c:7174 addrconf_sysctl_register+0x147/0x1a0 net/ipv6/addrconf.c:7211 ipv6_add_dev+0xc03/0x1150 net/ipv6/addrconf.c:456 addrconf_notify+0x582/0xde0 net/ipv6/addrconf.c:3600 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:391 call_netdevice_notifiers_info net/core/dev.c:2070 [inline] call_netdevice_notifiers_extack net/core/dev.c:2082 [inline] call_netdevice_notifiers+0x119/0x190 net/core/dev.c:2096 page last free stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] free_pages_prepare mm/page_alloc.c:1472 [inline] free_pcp_prepare mm/page_alloc.c:1544 [inline] free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534 free_unref_page+0xae/0x540 mm/page_alloc.c:3616 free_the_page mm/page_alloc.c:805 [inline] __free_pages+0x6c/0x100 mm/page_alloc.c:5898 __vunmap+0x86d/0xa00 mm/vmalloc.c:2660 __vfree mm/vmalloc.c:2709 [inline] vfree+0x8b/0xc0 mm/vmalloc.c:2740 kcov_put kernel/kcov.c:417 [inline] kcov_close+0x2b/0x50 kernel/kcov.c:519 __fput+0x20b/0x8b0 fs/file_table.c:311 ____fput+0x15/0x20 fs/file_table.c:339 task_work_run+0x127/0x190 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xa9e/0x27e0 kernel/exit.c:889 do_group_exit+0x141/0x310 kernel/exit.c:1003 __do_sys_exit_group kernel/exit.c:1014 [inline] __se_sys_exit_group kernel/exit.c:1012 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1012 x64_sys_call+0x832/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 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 Memory state around the buggy address: ffff888125c66f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888125c66f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888125c67000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888125c67080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc ffff888125c67100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ================================================================== EXT4-fs error (device loop2): ext4_ext_split:1074: inode #15: comm syz.2.832: p_ext > EXT_MAX_EXTENT! EXT4-fs (loop2): pa ffff8881348b8b28: logic 128, phys. 385, len 8 EXT4-fs error (device loop2): ext4_mb_release_inode_pa:4902: group 0, free 3, pa_free 2 EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 119 with max blocks 1 with error 117 EXT4-fs (loop2): This should not happen!! Data will be lost