On Tue, Apr 17, 2018 at 06:02:02PM -0700, syzbot wrote: > Hello, > > syzbot hit the following crash on upstream commit > a27fc14219f2e3c4a46ba9177b04d9b52c875532 (Mon Apr 16 21:07:39 2018 +0000) > Merge branch 'parisc-4.17-3' of > git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux > syzbot dashboard link: > https://syzkaller.appspot.com/bug?extid=c6f45f6af72a45097be2 > > So far this crash happened 2 times on upstream. > C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5638195895074816 > syzkaller reproducer: > https://syzkaller.appspot.com/x/repro.syz?id=5154296156913664 > Raw console output: > https://syzkaller.appspot.com/x/log.txt?id=5743820952043520 > Kernel config: > https://syzkaller.appspot.com/x/.config?id=-5914490758943236750 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+c6f45f6af72a45097be2@xxxxxxxxxxxxxxxxxxxxxxxxx > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > VFS: Busy inodes after unmount of fuse. Self-destruct in 5 seconds. Have a > nice day... > ================================================================== > BUG: KASAN: use-after-free in iput_final fs/inode.c:1489 [inline] > BUG: KASAN: use-after-free in iput+0xa05/0xa80 fs/inode.c:1545 > Read of size 8 at addr ffff8801d9752770 by task syzkaller802106/4482 > > CPU: 1 PID: 4482 Comm: syzkaller802106 Not tainted 4.17.0-rc1+ #6 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1b9/0x294 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+0x242/0x2fe mm/kasan/report.c:412 > __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 > iput_final fs/inode.c:1489 [inline] > iput+0xa05/0xa80 fs/inode.c:1545 > free_trace_uprobe+0xe2/0x1f0 kernel/trace/trace_uprobe.c:292 > destroy_local_trace_uprobe+0x63/0x7e kernel/trace/trace_uprobe.c:1395 > perf_uprobe_destroy+0xf2/0x130 kernel/trace/trace_event_perf.c:342 > _free_event+0x3ff/0x1430 kernel/events/core.c:4445 > put_event+0x48/0x60 kernel/events/core.c:4531 > perf_event_release_kernel+0x8bd/0xf90 kernel/events/core.c:4637 > perf_release+0x37/0x50 kernel/events/core.c:4647 > __fput+0x34d/0x890 fs/file_table.c:209 > ____fput+0x15/0x20 fs/file_table.c:243 > task_work_run+0x1e4/0x290 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0x1aee/0x2730 kernel/exit.c:865 > do_group_exit+0x16f/0x430 kernel/exit.c:968 > get_signal+0x886/0x1960 kernel/signal.c:2469 > do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 > exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162 > prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] > syscall_return_slowpath arch/x86/entry/common.c:265 [inline] > do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x4457b9 > RSP: 002b:00007f98cec58da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca > RAX: fffffffffffffe00 RBX: 0000000000000000 RCX: 00000000004457b9 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dac3c > RBP: 00000000006dac3c R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac38 > R13: 0030656c69662f2e R14: 00007f98cec599c0 R15: 0000000000000001 > > Allocated by task 4481: > 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:512 [inline] > kzalloc include/linux/slab.h:701 [inline] > alloc_super fs/super.c:186 [inline] > sget_userns+0x1c7/0xf20 fs/super.c:503 > sget+0x10b/0x150 fs/super.c:558 > mount_nodev+0x33/0x110 fs/super.c:1206 > fuse_mount+0x2c/0x40 fs/fuse/inode.c:1192 > mount_fs+0xae/0x328 fs/super.c:1268 > vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037 > vfs_kern_mount fs/namespace.c:1027 [inline] > do_new_mount fs/namespace.c:2517 [inline] > do_mount+0x564/0x3070 fs/namespace.c:2847 > ksys_mount+0x12d/0x140 fs/namespace.c:3063 > __do_sys_mount fs/namespace.c:3077 [inline] > __se_sys_mount fs/namespace.c:3074 [inline] > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3074 > do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 25: > 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 > destroy_super_work+0x40/0x50 fs/super.c:149 > process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 > worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 > kthread+0x345/0x410 kernel/kthread.c:238 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 > > The buggy address belongs to the object at ffff8801d9752740 > which belongs to the cache kmalloc-4096 of size 4096 > The buggy address is located 48 bytes inside of > 4096-byte region [ffff8801d9752740, ffff8801d9753740) > The buggy address belongs to the page: > page:ffffea000765d480 count:1 mapcount:0 mapping:ffff8801d9752740 index:0x0 > compound_mapcount: 0 > flags: 0x2fffc0000008100(slab|head) > raw: 02fffc0000008100 ffff8801d9752740 0000000000000000 0000000100000001 > raw: ffffea000765a1a0 ffffea00076665a0 ffff8801dac00dc0 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801d9752600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8801d9752680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ffff8801d9752700: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb > ^ > ffff8801d9752780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801d9752800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > This bug is generated by a dumb bot. It may contain errors. > See https://goo.gl/tpsmEJ for details. > Direct all questions to syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. > If you forgot to add the Reported-by tag, once the fix for this bug is > merged > into any tree, please reply to this email with: > #syz fix: exact-commit-title This was a reference counting bug in kernel/trace/trace_uprobe.c, fixed by commit 0c92c7a3c5d416: #syz fix: tracing: Fix bad use of igrab in trace_uprobe.c - Eric
