================================================================== BUG: KASAN: slab-use-after-free in pwq_release_workfn+0x253/0x260 kernel/workqueue.c:4124 Read of size 4 at addr ffff888024ca5dc0 by task pool_workqueue_/3 CPU: 0 PID: 3 Comm: pool_workqueue_ Not tainted 6.6.0-rc3-syzkaller-00214-ge402b08634b3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0x163/0x540 mm/kasan/report.c:475 kasan_report+0x175/0x1b0 mm/kasan/report.c:588 pwq_release_workfn+0x253/0x260 kernel/workqueue.c:4124 kthread_worker_fn+0x4ba/0xa90 kernel/kthread.c:823 kthread+0x2d3/0x370 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 Allocated by task 5158: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4f/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383 kmalloc include/linux/slab.h:599 [inline] kzalloc include/linux/slab.h:720 [inline] alloc_workqueue+0x172/0x1520 kernel/workqueue.c:4684 loop_configure+0x613/0x1250 drivers/block/loop.c:1058 lo_ioctl+0x8f5/0x2080 blkdev_ioctl+0x5cf/0x730 block/ioctl.c:630 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 5158: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4f/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1800 [inline] slab_free_freelist_hook mm/slub.c:1826 [inline] slab_free mm/slub.c:3809 [inline] __kmem_cache_free+0x25f/0x3b0 mm/slub.c:3822 alloc_workqueue+0xeba/0x1520 kernel/workqueue.c:4746 loop_configure+0x613/0x1250 drivers/block/loop.c:1058 lo_ioctl+0x8f5/0x2080 blkdev_ioctl+0x5cf/0x730 block/ioctl.c:630 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff888024ca5c00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 448 bytes inside of freed 512-byte region [ffff888024ca5c00, ffff888024ca5e00) The buggy address belongs to the physical page: page:ffffea0000932900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x24ca4 head:ffffea0000932900 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000840 ffff888012841c80 ffffea000088d800 dead000000000002 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2357, tgid 2357 (kworker/u4:7), ts 20453698064, free_ts 0 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1536 prep_new_page mm/page_alloc.c:1543 [inline] get_page_from_freelist+0x31db/0x3360 mm/page_alloc.c:3170 __alloc_pages+0x255/0x670 mm/page_alloc.c:4426 alloc_slab_page+0x6a/0x160 mm/slub.c:1870 allocate_slab mm/slub.c:2017 [inline] new_slab+0x84/0x2f0 mm/slub.c:2070 ___slab_alloc+0xc85/0x1310 mm/slub.c:3223 __slab_alloc mm/slub.c:3322 [inline] __slab_alloc_node mm/slub.c:3375 [inline] slab_alloc_node mm/slub.c:3468 [inline] __kmem_cache_alloc_node+0x1af/0x270 mm/slub.c:3517 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1114 kmalloc include/linux/slab.h:599 [inline] kzalloc include/linux/slab.h:720 [inline] alloc_bprm+0x56/0x900 fs/exec.c:1514 kernel_execve+0x96/0xa10 fs/exec.c:1989 call_usermodehelper_exec_async+0x233/0x370 kernel/umh.c:110 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 page_owner free stack trace missing Memory state around the buggy address: ffff888024ca5c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888024ca5d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888024ca5d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888024ca5e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888024ca5e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================