On 20/12/2020 01:24, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: a409ed15 Merge tag 'gpio-v5.11-1' of git://git.kernel.org/.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1425527b500000 > kernel config: https://syzkaller.appspot.com/x/.config?x=f7c39e7211134bc0 > dashboard link: https://syzkaller.appspot.com/bug?extid=fef004c4db2d363bacd3 > compiler: gcc (GCC) 10.1.0-syz 20200507 > > Unfortunately, I don't have any reproducer for this issue yet. #syz dup: WARNING in percpu_ref_kill_and_confirm (2) > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+fef004c4db2d363bacd3@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:938 [inline] > BUG: KASAN: use-after-free in __mutex_lock+0x102f/0x1110 kernel/locking/mutex.c:1103 > Read of size 8 at addr ffff888073de33e0 by task syz-executor.1/13101 > > CPU: 1 PID: 13101 Comm: syz-executor.1 Not tainted 5.10.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:120 > print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385 > __kasan_report mm/kasan/report.c:545 [inline] > kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562 > __mutex_lock_common kernel/locking/mutex.c:938 [inline] > __mutex_lock+0x102f/0x1110 kernel/locking/mutex.c:1103 > io_ring_ctx_wait_and_kill+0x21/0x450 fs/io_uring.c:8648 > io_uring_release+0x3e/0x50 fs/io_uring.c:8687 > __fput+0x283/0x920 fs/file_table.c:280 > task_work_run+0xdd/0x190 kernel/task_work.c:140 > exit_task_work include/linux/task_work.h:30 [inline] > do_exit+0xb89/0x2a00 kernel/exit.c:823 > do_group_exit+0x125/0x310 kernel/exit.c:920 > get_signal+0x3e9/0x2160 kernel/signal.c:2770 > arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811 > handle_signal_work kernel/entry/common.c:147 [inline] > exit_to_user_mode_loop kernel/entry/common.c:171 [inline] > exit_to_user_mode_prepare+0x124/0x200 kernel/entry/common.c:201 > __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] > syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x45e149 > Code: Unable to access opcode bytes at RIP 0x45e11f. > RSP: 002b:00007f2290236be8 EFLAGS: 00000206 ORIG_RAX: 00000000000001a9 > RAX: fffffffffffffff4 RBX: 0000000020000080 RCX: 000000000045e149 > RDX: 00000000200b0000 RSI: 0000000020000080 RDI: 0000000000000001 > RBP: 000000000119c080 R08: 0000000020000000 R09: 0000000020000000 > R10: 0000000020000100 R11: 0000000000000206 R12: 00000000200b0000 > R13: 00000000200a0000 R14: 0000000020000000 R15: 0000000020000100 > > Allocated by task 13101: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_set_track mm/kasan/common.c:56 [inline] > __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461 > kmalloc include/linux/slab.h:552 [inline] > kzalloc include/linux/slab.h:682 [inline] > io_ring_ctx_alloc fs/io_uring.c:1268 [inline] > io_uring_create fs/io_uring.c:9480 [inline] > io_uring_setup+0x1d5b/0x38b0 fs/io_uring.c:9613 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Freed by task 37: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 > kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:352 > __kasan_slab_free+0x102/0x140 mm/kasan/common.c:422 > slab_free_hook mm/slub.c:1544 [inline] > slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577 > slab_free mm/slub.c:3140 [inline] > kfree+0xdb/0x3c0 mm/slub.c:4122 > process_one_work+0x98d/0x1630 kernel/workqueue.c:2275 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 > kthread+0x3b1/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 > > Last potentially related work creation: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 > kasan_record_aux_stack+0xc0/0xf0 mm/kasan/generic.c:343 > insert_work+0x48/0x370 kernel/workqueue.c:1331 > __queue_work+0x5c1/0xfb0 kernel/workqueue.c:1497 > queue_work_on+0xc7/0xd0 kernel/workqueue.c:1524 > io_uring_create fs/io_uring.c:9586 [inline] > io_uring_setup+0x1358/0x38b0 fs/io_uring.c:9613 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > The buggy address belongs to the object at ffff888073de3000 > which belongs to the cache kmalloc-2k of size 2048 > The buggy address is located 992 bytes inside of > 2048-byte region [ffff888073de3000, ffff888073de3800) > The buggy address belongs to the page: > page:000000002686ff6f refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x73de0 > head:000000002686ff6f order:3 compound_mapcount:0 compound_pincount:0 > flags: 0xfff00000010200(slab|head) > raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010842000 > raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff888073de3280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888073de3300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff888073de3380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff888073de3400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888073de3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > -- Pavel Begunkov
