loop2: detected capacity change from 0 to 1024 EXT4-fs (loop2): ext4_check_descriptors: Inode bitmap for group 0 overlaps superblock EXT4-fs (loop2): ext4_check_descriptors: Checksum for group 0 failed (42152!=20869) EXT4-fs error (device loop2): ext4_get_journal_inode:5724: inode #5: comm syz.2.4959: unexpected bad inode w/o EXT4_IGET_BAD ================================================================== BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:930 [inline] BUG: KASAN: use-after-free in enqueue_timer+0xae/0x480 kernel/time/timer.c:611 Write of size 8 at addr ffff88811f29c4c0 by task syz.2.4959/21527 CPU: 1 PID: 21527 Comm: syz.2.4959 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 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_store8_noabort+0x17/0x20 mm/kasan/report_generic.c:356 hlist_add_head include/linux/list.h:930 [inline] enqueue_timer+0xae/0x480 kernel/time/timer.c:611 __mod_timer+0x79f/0xb30 kernel/time/timer.c:-1 mod_timer+0x1f/0x30 kernel/time/timer.c:1172 ext4_update_super+0xa54/0xe40 fs/ext4/super.c:6070 ext4_commit_super+0xe3/0x4b0 fs/ext4/super.c:6089 ext4_handle_error+0x5c8/0x860 fs/ext4/super.c:678 __ext4_error_inode+0x2ce/0x560 fs/ext4/super.c:811 check_igot_inode+0x1a8/0x1d0 fs/ext4/inode.c:4817 __ext4_iget+0x2a58/0x3d70 fs/ext4/inode.c:5134 ext4_get_journal_inode+0x33/0x1c0 fs/ext4/super.c:5724 ext4_calculate_overhead+0xf05/0x1230 fs/ext4/super.c:4175 __ext4_fill_super fs/ext4/super.c:5369 [inline] ext4_fill_super+0x598e/0x7970 fs/ext4/super.c:5655 get_tree_bdev+0x444/0x680 fs/super.c:1368 ext4_get_tree+0x1c/0x20 fs/ext4/super.c:5685 vfs_get_tree+0x9a/0x270 fs/super.c:1575 do_new_mount+0x25a/0xa20 fs/namespace.c:3069 path_mount+0x675/0x1010 fs/namespace.c:3399 do_mount fs/namespace.c:3412 [inline] __do_sys_mount fs/namespace.c:3620 [inline] __se_sys_mount+0x318/0x380 fs/namespace.c:3597 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3597 x64_sys_call+0x65d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166 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: 0033:0x7fccf1b9066a Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 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:00007fccf2a30e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007fccf2a30ef0 RCX: 00007fccf1b9066a RDX: 00002000000000c0 RSI: 0000200000000040 RDI: 00007fccf2a30eb0 RBP: 00002000000000c0 R08: 00007fccf2a30ef0 R09: 0000000000000011 R10: 0000000000000011 R11: 0000000000000246 R12: 0000200000000040 R13: 00007fccf2a30eb0 R14: 0000000000000610 R15: 0000200000000100 Allocated by task 20875: 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_kmalloc mm/kasan/common.c:379 [inline] __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:388 kasan_kmalloc include/linux/kasan.h:212 [inline] kmalloc_trace+0x40/0xb0 mm/slab_common.c:1033 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] ext4_alloc_sbi fs/ext4/super.c:4263 [inline] ext4_fill_super+0x107/0x7970 fs/ext4/super.c:5642 get_tree_bdev+0x444/0x680 fs/super.c:1368 ext4_get_tree+0x1c/0x20 fs/ext4/super.c:5685 vfs_get_tree+0x9a/0x270 fs/super.c:1575 do_new_mount+0x25a/0xa20 fs/namespace.c:3069 path_mount+0x675/0x1010 fs/namespace.c:3399 do_mount fs/namespace.c:3412 [inline] __do_sys_mount fs/namespace.c:3620 [inline] __se_sys_mount+0x318/0x380 fs/namespace.c:3597 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3597 x64_sys_call+0x65d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166 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 Freed by task 20772: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:241 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:249 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 ext4_put_super+0x9b6/0xac0 fs/ext4/super.c:1313 generic_shutdown_super+0x15f/0x370 fs/super.c:503 kill_block_super+0x7f/0xf0 fs/super.c:1472 deactivate_locked_super+0xb5/0x120 fs/super.c:334 deactivate_super+0xaf/0xe0 fs/super.c:365 cleanup_mnt+0x45f/0x4e0 fs/namespace.c:1182 __cleanup_mnt+0x19/0x20 fs/namespace.c:1189 task_work_run+0x1db/0x240 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0xa25/0x2650 kernel/exit.c:886 do_group_exit+0x210/0x2d0 kernel/exit.c:1028 __do_sys_exit_group kernel/exit.c:1039 [inline] __se_sys_exit_group kernel/exit.c:1037 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1037 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 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 ffff88811f29c000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 1216 bytes inside of 4096-byte region [ffff88811f29c000, ffff88811f29d000) The buggy address belongs to the physical page: page:ffffea00047ca600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11f298 head:ffffea00047ca600 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 ffffea0004584a00 dead000000000002 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 19811, tgid 19810 (syz.9.4546), ts 2341807948587, free_ts 2341079442221 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+0x203/0x2c0 mm/slub.c:3423 __do_kmalloc_node mm/slab_common.c:937 [inline] __kmalloc+0xa1/0x1e0 mm/slab_common.c:951 kmalloc_array include/linux/slab.h:615 [inline] genl_family_rcv_msg_attrs_parse+0xac/0x2a0 net/netlink/genetlink.c:560 genl_family_rcv_msg_doit+0xd1/0x350 net/netlink/genetlink.c:734 genl_family_rcv_msg net/netlink/genetlink.c:833 [inline] genl_rcv_msg+0x5ea/0x770 net/netlink/genetlink.c:850 netlink_rcv_skb+0x1f2/0x440 net/netlink/af_netlink.c:2521 genl_rcv+0x28/0x40 net/netlink/genetlink.c:861 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x8ab/0xa30 net/netlink/af_netlink.c:1345 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+0x8f/0x530 mm/page_alloc.c:3687 free_the_page mm/page_alloc.c:836 [inline] __free_pages+0x67/0x100 mm/page_alloc.c:5957 __free_slab+0xca/0x1a0 mm/slub.c:2044 free_slab mm/slub.c:2059 [inline] discard_slab mm/slub.c:2065 [inline] __unfreeze_partials+0x160/0x190 mm/slub.c:2614 put_cpu_partial+0xa9/0x100 mm/slub.c:2690 __slab_free+0x1c4/0x280 mm/slub.c:3589 do_slab_free mm/slub.c:3666 [inline] ___cache_free+0xbf/0xd0 mm/slub.c:3722 qlink_free mm/kasan/quarantine.c:168 [inline] qlist_free_all+0xc6/0x140 mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0x24/0x80 mm/kasan/common.c:310 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] slab_alloc mm/slub.c:3392 [inline] __kmem_cache_alloc_lru mm/slub.c:3399 [inline] kmem_cache_alloc+0x16e/0x330 mm/slub.c:3408 getname_flags+0xb9/0x500 fs/namei.c:139 getname fs/namei.c:218 [inline] __do_sys_symlinkat fs/namei.c:4516 [inline] __se_sys_symlinkat fs/namei.c:4513 [inline] __x64_sys_symlinkat+0x7c/0xb0 fs/namei.c:4513 x64_sys_call+0x282/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:267 Memory state around the buggy address: ffff88811f29c380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811f29c400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88811f29c480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88811f29c500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88811f29c580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== EXT4-fs (loop2): no journal found EXT4-fs (loop2): can't get journal size EXT4-fs (loop2): mounted filesystem without journal. Quota mode: writeback.