Hello, I found the following issue using syzkaller on: HEAD commit : e60276b8c11ab4a8be23807bc67b04 8cfb937dfa (v6.0.8) git tree: stable C Reproducer : https://gist.github.com/oswalpalash/bed0eba75def3cdd34a285428e9bcdc4 Kernel .config : https://gist.github.com/oswalpalash/0962c70d774e5ec736a047bba917cecb Console log : ================================================================== BUG: KASAN: use-after-free in __list_del_entry_valid+0xf2/0x110 Read of size 8 at addr ffff8880273c4358 by task syz-executor.1/6475 CPU: 0 PID: 6475 Comm: syz-executor.1 Not tainted 6.0.8-pasta #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0xcd/0x134 print_report.cold+0xe5/0x63a kasan_report+0x8a/0x1b0 __list_del_entry_valid+0xf2/0x110 inode_cgwb_move_to_attached+0x2ee/0x4e0 writeback_single_inode+0x3fa/0x510 write_inode_now+0x16a/0x1e0 blkdev_flush_mapping+0x168/0x220 blkdev_put_whole+0xd1/0xf0 blkdev_put+0x29b/0x700 deactivate_locked_super+0x8c/0xf0 deactivate_super+0xad/0xd0 cleanup_mnt+0x347/0x4b0 task_work_run+0xe0/0x1a0 exit_to_user_mode_prepare+0x25d/0x270 syscall_exit_to_user_mode+0x19/0x50 do_syscall_64+0x42/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f22bd29143b Code: ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 90 f3 0f 1e fa 31 f6 e9 05 00 00 00 0f 1f 44 00 00 f3 0f 1e fa b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe505103b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f22bd29143b RDX: 00007f22bd228a90 RSI: 000000000000000a RDI: 00007ffe50510480 RBP: 00007ffe50510480 R08: 00007f22bd2fba1f R09: 00007ffe50510240 R10: 00000000fffffffb R11: 0000000000000246 R12: 00007f22bd2fb9f8 R13: 00007ffe50511520 R14: 0000555556f4bd90 R15: 0000000000000032 </TASK> Allocated by task 7810: kasan_save_stack+0x1e/0x40 __kasan_slab_alloc+0x85/0xb0 kmem_cache_alloc_lru+0x25b/0xfb0 fat_alloc_inode+0x23/0x1e0 alloc_inode+0x61/0x1e0 new_inode_pseudo+0x13/0x80 new_inode+0x1b/0x40 fat_build_inode+0x146/0x2d0 vfat_create+0x249/0x390 lookup_open+0x10bc/0x1640 path_openat+0xa42/0x2840 do_filp_open+0x1ca/0x2a0 do_sys_openat2+0x61b/0x990 do_sys_open+0xc3/0x140 do_syscall_64+0x35/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 16: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_set_free_info+0x20/0x30 __kasan_slab_free+0xf5/0x180 kmem_cache_free.part.0+0xfc/0x4a0 i_callback+0x3f/0x70 rcu_core+0x785/0x1720 __do_softirq+0x1d0/0x908 Last potentially related work creation: kasan_save_stack+0x1e/0x40 __kasan_record_aux_stack+0x7e/0x90 call_rcu+0x99/0x740 destroy_inode+0x129/0x1b0 iput.part.0+0x5cd/0x800 iput+0x58/0x70 dentry_unlink_inode+0x2e2/0x4a0 __dentry_kill+0x374/0x5e0 dput+0x656/0xbe0 __fput+0x3cc/0xa90 task_work_run+0xe0/0x1a0 exit_to_user_mode_prepare+0x25d/0x270 syscall_exit_to_user_mode+0x19/0x50 do_syscall_64+0x42/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff8880273c4080 which belongs to the cache fat_inode_cache of size 1488 The buggy address is located 728 bytes inside of 1488-byte region [ffff8880273c4080, ffff8880273c4650) The buggy address belongs to the physical page: page:ffffea00009cf100 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880273c4ffe pfn:0x273c4 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea00009cf0c8 ffff88801820e450 ffff888103e00e00 raw: ffff8880273c4ffe ffff8880273c4080 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Reclaimable, gfp_mask 0x242050(__GFP_IO|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE|__GFP_RECLAIMABLE), pid 7810, tgid 7808 (syz-executor.1), ts 50543388569, free_ts 21285403579 prep_new_page+0x2c6/0x350 get_page_from_freelist+0xae9/0x3a80 __alloc_pages+0x321/0x710 cache_grow_begin+0x75/0x360 kmem_cache_alloc_lru+0xe72/0xfb0 fat_alloc_inode+0x23/0x1e0 alloc_inode+0x61/0x1e0 new_inode_pseudo+0x13/0x80 new_inode+0x1b/0x40 fat_fill_super+0x1c37/0x3710 mount_bdev+0x34d/0x410 legacy_get_tree+0x105/0x220 vfs_get_tree+0x89/0x2f0 path_mount+0x121b/0x1cb0 do_mount+0xf3/0x110 __x64_sys_mount+0x18f/0x230 page last free stack trace: free_pcp_prepare+0x5ab/0xd00 free_unref_page+0x19/0x410 slab_destroy+0x14/0x50 slabs_destroy+0x6a/0x90 ___cache_free+0x1e3/0x3b0 qlist_free_all+0x51/0x1c0 kasan_quarantine_reduce+0x13d/0x180 __kasan_slab_alloc+0x97/0xb0 kmem_cache_alloc+0x204/0xcc0 getname_flags+0xd2/0x5b0 vfs_fstatat+0x73/0xb0 __do_sys_newlstat+0x8b/0x110 do_syscall_64+0x35/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd Memory state around the buggy address: ffff8880273c4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880273c4280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880273c4300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880273c4380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880273c4400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
