On Tue, Jan 30, 2018 at 01:52:02AM -0800, syzbot wrote: > syzbot has found reproducer for the following crash on upstream commit > 6304672b7f0a5c010002e63a075160856dc4f88d (Tue Jan 30 03:08:02 2018 +0000) > Merge branch 'x86-pti-for-linus' of > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip > > So far this crash happened 172 times on linux-next, mmots, upstream. > C reproducer is attached. > syzkaller reproducer is attached. > Raw console output is attached. > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: > syzbot+20eb18b1ffc36152b5608d41ab3bf6bd18c23aa7@xxxxxxxxxxxxxxxxxxxxxxxxx > It will help syzbot understand when the bug is fixed. > > ================================================================== > BUG: KASAN: use-after-free in perf_trace_lock_acquire+0x5b7/0x980 > include/trace/events/lock.h:13 > Read of size 8 at addr ffff8801b48e50b8 by task syzkaller241108/8081 > > CPU: 1 PID: 8081 Comm: syzkaller241108 Not tainted 4.15.0+ #286 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:53 > print_address_description+0x73/0x250 mm/kasan/report.c:252 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x25b/0x340 mm/kasan/report.c:409 > __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 > perf_trace_lock_acquire+0x5b7/0x980 include/trace/events/lock.h:13 > trace_lock_acquire include/trace/events/lock.h:13 [inline] > lock_acquire+0x394/0x580 kernel/locking/lockdep.c:3914 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 > remove_wait_queue+0x81/0x350 kernel/sched/wait.c:50 > vhost_poll_stop drivers/vhost/vhost.c:230 [inline] > vhost_dev_stop+0x15c/0x2a0 drivers/vhost/vhost.c:566 > vhost_net_release+0x6e/0x190 drivers/vhost/net.c:998 > __fput+0x327/0x7e0 fs/file_table.c:210 > ____fput+0x15/0x20 fs/file_table.c:244 > task_work_run+0x199/0x270 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0x9bb/0x1ad0 kernel/exit.c:865 > do_group_exit+0x149/0x400 kernel/exit.c:968 > get_signal+0x73f/0x16c0 kernel/signal.c:2335 > do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809 > exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 > entry_SYSCALL_64_fastpath+0x9e/0xa0 > RIP: 0033:0x44bff9 > RSP: 002b:00007ff890dd4da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca > RAX: fffffffffffffe00 RBX: 0000000000700054 RCX: 000000000044bff9 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000700054 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000700050 > R13: 6f68762f7665642f R14: 00007ff890dd59c0 R15: 0000000000000007 > > Allocated by task 8054: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 > kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3610 > kmalloc include/linux/slab.h:499 [inline] > eventfd_file_create.part.3+0x96/0x250 fs/eventfd.c:441 > eventfd_file_create fs/eventfd.c:483 [inline] > SYSC_eventfd2 fs/eventfd.c:468 [inline] > SyS_eventfd2 fs/eventfd.c:458 [inline] > SYSC_eventfd fs/eventfd.c:485 [inline] > SyS_eventfd+0x2c/0x80 fs/eventfd.c:483 > entry_SYSCALL_64_fastpath+0x29/0xa0 > > Freed by task 8081: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 > __cache_free mm/slab.c:3488 [inline] > kfree+0xd6/0x260 mm/slab.c:3803 > eventfd_free_ctx fs/eventfd.c:72 [inline] > eventfd_free fs/eventfd.c:79 [inline] > kref_put include/linux/kref.h:70 [inline] > eventfd_ctx_put+0x26/0x30 fs/eventfd.c:104 > eventfd_release+0x52/0x60 fs/eventfd.c:113 > __fput+0x327/0x7e0 fs/file_table.c:210 > ____fput+0x15/0x20 fs/file_table.c:244 > task_work_run+0x199/0x270 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0x9bb/0x1ad0 kernel/exit.c:865 > do_group_exit+0x149/0x400 kernel/exit.c:968 > get_signal+0x73f/0x16c0 kernel/signal.c:2335 > do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809 > exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 > entry_SYSCALL_64_fastpath+0x9e/0xa0 > > The buggy address belongs to the object at ffff8801b48e5080 > which belongs to the cache kmalloc-96 of size 96 > The buggy address is located 56 bytes inside of > 96-byte region [ffff8801b48e5080, ffff8801b48e50e0) > The buggy address belongs to the page: > page:ffffea0006d23940 count:1 mapcount:0 mapping:ffff8801b48e5000 index:0x0 > flags: 0x2fffc0000000100(slab) > raw: 02fffc0000000100 ffff8801b48e5000 0000000000000000 0000000100000020 > raw: ffffea0006a220e0 ffffea0006cc4320 ffff8801db0004c0 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801b48e4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8801b48e5000: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc > > ffff8801b48e5080: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ^ > ffff8801b48e5100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ffff8801b48e5180: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ================================================================== No longer occurring, seems this was yet another report of the vhost bug fixed by commit 4cd879515d68: #syz fix: vhost_net: stop device during reset owner - Eric
