Hi, Syzkaller found the following issue: HEAD commit: 75acfdb Linux 5.16-rc8 git tree: upstream console output: https://pastebin.com/raw/yHnKW716 kernel config: https://pastebin.com/raw/XsnKfdRt And hope the report log can help you. ================================================================== BUG: KASAN: use-after-free in start_motor+0x31b/0x3f0 Read of size 4 at addr ffff88801961c800 by task kworker/u16:1/10 CPU: 0 PID: 10 Comm: kworker/u16:1 Not tainted 5.16.0-rc8+ #10 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: floppy fd_timer_workfn Call Trace: <TASK> dump_stack_lvl+0xcd/0x134 print_address_description.constprop.0.cold+0x93/0x347 kasan_report.cold+0x83/0xdf start_motor+0x31b/0x3f0 floppy_ready+0x7f/0x19b0 process_one_work+0x9df/0x16a0 worker_thread+0x90/0xe20 kthread+0x405/0x4f0 ret_from_fork+0x1f/0x30 </TASK> Allocated by task 17012: kasan_save_stack+0x1e/0x50 __kasan_kmalloc+0xa9/0xd0 kmem_cache_alloc_trace+0x198/0x390 fd_locked_ioctl+0xa33/0x23d0 fd_ioctl+0x35/0x50 blkdev_ioctl+0x37a/0x800 __x64_sys_ioctl+0x193/0x200 do_syscall_64+0x35/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 17012: kasan_save_stack+0x1e/0x50 kasan_set_track+0x21/0x30 kasan_set_free_info+0x20/0x30 __kasan_slab_free+0x100/0x140 kfree+0x107/0x4c0 raw_cmd_free+0x72/0x140 fd_locked_ioctl+0x19b4/0x23d0 fd_ioctl+0x35/0x50 blkdev_ioctl+0x37a/0x800 __x64_sys_ioctl+0x193/0x200 do_syscall_64+0x35/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88801961c800 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 0 bytes inside of 128-byte region [ffff88801961c800, ffff88801961c880) The buggy address belongs to the page: page:ffffea0000658700 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1961c head:ffffea0000658700 order:1 compound_mapcount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c428c0 raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 16049, ts 140600618188, free_ts 140590103353 prep_new_page+0x1a6/0x240 get_page_from_freelist+0x1eec/0x3b50 __alloc_pages+0x30c/0x6e0 alloc_pages+0x115/0x240 new_slab+0x35e/0x4b0 ___slab_alloc+0xae6/0x1120 __slab_alloc.isra.0+0x4d/0xa0 __kmalloc+0x345/0x3d0 tomoyo_supervisor+0xca7/0xe30 tomoyo_path_permission+0x270/0x3a0 tomoyo_path_perm+0x352/0x420 tomoyo_path_symlink+0x94/0xe0 security_path_symlink+0xdf/0x150 do_symlinkat+0x107/0x2a0 __x64_sys_symlink+0x75/0x90 do_syscall_64+0x35/0xb0 page last free stack trace: free_pcp_prepare+0x474/0x9f0 free_unref_page+0x19/0x5b0 __unfreeze_partials+0x343/0x360 qlist_free_all+0x5a/0xc0 kasan_quarantine_reduce+0x13d/0x180 __kasan_slab_alloc+0xa2/0xc0 slab_post_alloc_hook+0x4d/0x4a0 __kmalloc+0x190/0x3d0 tomoyo_supervisor+0xca7/0xe30 tomoyo_path_permission+0x270/0x3a0 tomoyo_path_perm+0x2fc/0x420 tomoyo_path_unlink+0x8e/0xd0 security_path_unlink+0xd7/0x150 do_unlinkat+0x369/0x660 __x64_sys_unlink+0x3e/0x50 do_syscall_64+0x35/0xb0 Memory state around the buggy address: ffff88801961c700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801961c780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88801961c800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801961c880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88801961c900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================
