From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f197.google.com ([209.85.223.197]:40286 "EHLO mail-io0-f197.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388231AbeGKQoL (ORCPT ); Wed, 11 Jul 2018 12:44:11 -0400 Received: by mail-io0-f197.google.com with SMTP id r10-v6so22321861ioh.7 for ; Wed, 11 Jul 2018 09:39:02 -0700 (PDT) MIME-Version: 1.0 Date: Wed, 11 Jul 2018 09:39:02 -0700 Message-ID: <0000000000005e2bf90570bbe2ab@google.com> Subject: KASAN: use-after-free Read in ep_scan_ready_list From: syzbot To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hello, syzbot found the following crash on: HEAD commit: 98be45067040 Add linux-next specific files for 20180711 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=10de4efc400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3f3b3673fec35d01 dashboard link: https://syzkaller.appspot.com/bug?extid=78b902c73c69102cb767 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13d5291c400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ed430c400000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+78b902c73c69102cb767@syzkaller.appspotmail.com random: sshd: uninitialized urandom read (32 bytes read) IPVS: ftp: loaded support on port[0] = 21 ================================================================== BUG: KASAN: use-after-free in atomic64_read include/asm-generic/atomic-instrumented.h:27 [inline] BUG: KASAN: use-after-free in atomic_long_read include/asm-generic/atomic-long.h:47 [inline] BUG: KASAN: use-after-free in __mutex_trylock_or_owner kernel/locking/mutex.c:84 [inline] BUG: KASAN: use-after-free in __mutex_trylock kernel/locking/mutex.c:125 [inline] BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:927 [inline] BUG: KASAN: use-after-free in __mutex_lock+0x185/0x1680 kernel/locking/mutex.c:1073 Read of size 8 at addr ffff8801c62d85b8 by task kworker/0:2/2137 CPU: 0 PID: 2137 Comm: kworker/0:2 Not tainted 4.18.0-rc4-next-20180711+ #4 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events p9_poll_workfn Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272 atomic64_read include/asm-generic/atomic-instrumented.h:27 [inline] atomic_long_read include/asm-generic/atomic-long.h:47 [inline] __mutex_trylock_or_owner kernel/locking/mutex.c:84 [inline] __mutex_trylock kernel/locking/mutex.c:125 [inline] __mutex_lock_common kernel/locking/mutex.c:927 [inline] __mutex_lock+0x185/0x1680 kernel/locking/mutex.c:1073 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 ep_scan_ready_list+0xb77/0xf50 fs/eventpoll.c:681 ep_eventpoll_poll+0x192/0x200 fs/eventpoll.c:937 vfs_poll include/linux/poll.h:86 [inline] p9_fd_poll+0x1ce/0x2b0 net/9p/trans_fd.c:248 p9_poll_mux net/9p/trans_fd.c:617 [inline] p9_poll_workfn+0x463/0x6d0 net/9p/trans_fd.c:1107 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296 kthread+0x345/0x410 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 Allocated by task 4472: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:707 [inline] ep_alloc fs/eventpoll.c:1016 [inline] do_epoll_create+0x170/0x5c0 fs/eventpoll.c:1952 __do_sys_epoll_create1 fs/eventpoll.c:1983 [inline] __se_sys_epoll_create1 fs/eventpoll.c:1981 [inline] __x64_sys_epoll_create1+0x31/0x40 fs/eventpoll.c:1981 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 4472: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xd9/0x260 mm/slab.c:3813 ep_free+0x273/0x310 fs/eventpoll.c:856 ep_eventpoll_release+0x44/0x60 fs/eventpoll.c:864 __fput+0x35d/0x930 fs/file_table.c:252 ____fput+0x15/0x20 fs/file_table.c:288 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1b08/0x2750 kernel/exit.c:869 do_group_exit+0x177/0x440 kernel/exit.c:972 get_signal+0x88e/0x1970 kernel/signal.c:2467 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8801c62d8580 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 56 bytes inside of 512-byte region [ffff8801c62d8580, ffff8801c62d8780) The buggy address belongs to the page: page:ffffea000718b600 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea0006b54dc8 ffffea000764a188 ffff8801da800940 raw: 0000000000000000 ffff8801c62d8080 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801c62d8480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801c62d8500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8801c62d8580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801c62d8600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801c62d8680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This bug 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@googlegroups.com. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot. syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches