BUG: KASAN: use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2601 [inline] BUG: KASAN: use-after-free in ext4_ext_remove_space+0x353c/0x4180 fs/ext4/extents.c:2939 Read of size 4 at addr ffff888122cb2c18 by task syz-executor/468 CPU: 0 PID: 468 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+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0xee/0x150 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_rm_leaf fs/ext4/extents.c:2601 [inline] ext4_ext_remove_space+0x353c/0x4180 fs/ext4/extents.c:2939 ext4_ext_truncate+0x1a3/0x250 fs/ext4/extents.c:4473 ext4_truncate+0x9a6/0xfa0 fs/ext4/inode.c:4287 ext4_evict_inode+0xcb9/0x1450 fs/ext4/inode.c:290 evict+0x485/0x870 fs/inode.c:650 iput_final fs/inode.c:1779 [inline] iput+0x635/0x7c0 fs/inode.c:1805 do_unlinkat+0x375/0x6b0 fs/namei.c:4363 __do_sys_unlink fs/namei.c:4404 [inline] __se_sys_unlink fs/namei.c:4402 [inline] __x64_sys_unlink+0x49/0x50 fs/namei.c:4402 x64_sys_call+0x878/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:88 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: 0033:0x7f9a28398577 Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffda15c8d98 EFLAGS: 00000206 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9a28398577 RDX: 00007ffda15c8dc0 RSI: 00007ffda15c8e50 RDI: 00007ffda15c8e50 RBP: 00007ffda15c8e50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffda15c9f40 R13: 00007f9a2841bd7d R14: 000000000000b994 R15: 00007ffda15cb010 Allocated by task 305: 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_kmalloc mm/kasan/common.c:512 [inline] __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:521 kasan_kmalloc include/linux/kasan.h:227 [inline] __kmalloc_track_caller+0x13c/0x2c0 mm/slub.c:4959 kmemdup+0x26/0x60 mm/util.c:132 __devinet_sysctl_register+0xad/0x390 net/ipv4/devinet.c:2592 devinet_sysctl_register+0x169/0x1e0 net/ipv4/devinet.c:2644 inetdev_init+0x2b9/0x500 net/ipv4/devinet.c:284 inetdev_event+0x1f8/0x10a0 net/ipv4/devinet.c:1544 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:2057 [inline] call_netdevice_notifiers_extack net/core/dev.c:2069 [inline] call_netdevice_notifiers+0x111/0x190 net/core/dev.c:2083 register_netdevice+0x1039/0x13a0 net/core/dev.c:10436 register_netdev+0x3e/0x50 net/core/dev.c:10529 vti6_init_net+0x2c0/0x380 net/ipv6/ip6_vti.c:1164 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:138 setup_net+0x344/0xa90 net/core/net_namespace.c:332 copy_net_ns+0x355/0x5c0 net/core/net_namespace.c:476 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:226 ksys_unshare+0x4ac/0x7b0 kernel/fork.c:3242 __do_sys_unshare kernel/fork.c:3316 [inline] __se_sys_unshare kernel/fork.c:3314 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3314 x64_sys_call+0x442/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:273 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 8: 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] kfree+0xc4/0x270 mm/slub.c:4588 __devinet_sysctl_unregister net/ipv4/devinet.c:2628 [inline] devinet_sysctl_unregister net/ipv4/devinet.c:2655 [inline] inetdev_destroy net/ipv4/devinet.c:327 [inline] inetdev_event+0x7a5/0x10a0 net/ipv4/devinet.c:1612 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:2057 [inline] call_netdevice_notifiers_extack net/core/dev.c:2069 [inline] call_netdevice_notifiers net/core/dev.c:2083 [inline] unregister_netdevice_many+0xfb8/0x1990 net/core/dev.c:11150 vti6_exit_batch_net+0x26a/0x2b0 net/ipv6/ip6_vti.c:1190 ops_exit_list net/core/net_namespace.c:177 [inline] cleanup_net+0x602/0xad0 net/core/net_namespace.c:599 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472 kthread+0x411/0x500 kernel/kthread.c:337 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 The buggy address belongs to the object at ffff888122cb2000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 3096 bytes inside of 4096-byte region [ffff888122cb2000, ffff888122cb3000) The buggy address belongs to the 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 ffff888100043380 raw: 0000000000000000 0000000000040004 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 305, ts 24843504223, free_ts 15796115459 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+0x2cc5/0x2d50 mm/page_alloc.c:4485 __alloc_pages+0x18f/0x440 mm/page_alloc.c:5808 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_trace+0x146/0x270 mm/slub.c:3272 kmalloc include/linux/slab.h:619 [inline] kzalloc include/linux/slab.h:750 [inline] kobject_uevent_env+0x272/0x700 lib/kobject_uevent.c:539 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 device_add+0xa40/0xed0 drivers/base/core.c:3403 netdev_register_kobject+0x179/0x320 net/core/net-sysfs.c:2014 register_netdevice+0xdfa/0x13a0 net/core/dev.c:10405 register_netdev+0x3e/0x50 net/core/dev.c:10529 vti6_init_net+0x2c0/0x380 net/ipv6/ip6_vti.c:1164 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:138 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+0xa2/0x550 mm/page_alloc.c:3616 free_the_page mm/page_alloc.c:805 [inline] free_compound_page+0x78/0xa0 mm/page_alloc.c:828 destroy_compound_page include/linux/mm.h:1000 [inline] __put_compound_page+0x77/0xb0 mm/swap.c:111 __put_page+0xbc/0xe0 mm/swap.c:127 put_page include/linux/mm.h:1306 [inline] __skb_frag_unref include/linux/skbuff.h:3275 [inline] skb_release_data+0x3d3/0xa10 net/core/skbuff.c:673 skb_release_all net/core/skbuff.c:743 [inline] __kfree_skb+0x50/0x70 net/core/skbuff.c:757 sk_eat_skb include/net/sock.h:2786 [inline] tcp_recvmsg_locked+0x14ac/0x2640 net/ipv4/tcp.c:2517 tcp_recvmsg+0x21b/0x720 net/ipv4/tcp.c:2563 inet_recvmsg+0x134/0x470 net/ipv4/af_inet.c:861 sock_recvmsg_nosec net/socket.c:966 [inline] sock_recvmsg net/socket.c:984 [inline] sock_read_iter+0x2a2/0x340 net/socket.c:1057 call_read_iter include/linux/fs.h:2206 [inline] new_sync_read fs/read_write.c:404 [inline] vfs_read+0x68b/0xbe0 fs/read_write.c:485 ksys_read+0x140/0x240 fs/read_write.c:623 __do_sys_read fs/read_write.c:633 [inline] __se_sys_read fs/read_write.c:631 [inline] __x64_sys_read+0x7b/0x90 fs/read_write.c:631 x64_sys_call+0x96d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 Memory state around the buggy address: ffff888122cb2b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888122cb2b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888122cb2c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888122cb2c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888122cb2d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== EXT4-fs error (device loop2): mb_free_blocks:1860: group 0, inode 20: block 241:freeing already freed block (bit 15); block bitmap corrupt. EXT4-fs error (device loop2): mb_free_blocks:1860: group 0, inode 20: block 241:freeing already freed block (bit 15); block bitmap corrupt. EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 281470681817008, count = 16 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 281470681814844, count = 2177 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 281470681814832, count = 16 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 0, count = 38 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 0, count = 16 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 281470682112896, count = 16 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 281470682110720, count = 2177 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 0, count = 16 EXT4-fs error (device loop2): ext4_free_blocks:6218: comm syz-executor: Freeing blocks not in datazone - block = 0, count = 3 EXT4-fs error (device loop2): mb_free_blocks:1860: group 0, inode 20: block 241:freeing already freed block (bit 15); block bitmap corrupt.