From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752885AbdLMAF0 (ORCPT ); Tue, 12 Dec 2017 19:05:26 -0500 Received: from mail-it0-f45.google.com ([209.85.214.45]:43142 "EHLO mail-it0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752766AbdLMAFZ (ORCPT ); Tue, 12 Dec 2017 19:05:25 -0500 X-Google-Smtp-Source: ACJfBou7mO7z8ZnDOBN3HvgPf5EJDHEGrythLBTjiW7FgH9SdOIgJbVXkveiXk/uL0za9+FWt0s5fw== Date: Tue, 12 Dec 2017 16:05:17 -0800 From: Eric Biggers To: syzbot Cc: gregkh@linuxfoundation.org, arve@android.com, tkjos@android.com, maco@android.com, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: binder epoll bug (was KASAN: use-after-free Read in __lock_acquire (2)) Message-ID: <20171213000517.GB62138@gmail.com> References: <001a1147c73265e0a2055e43711e@google.com> <001a1149750a83b8db055f5db0d2@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <001a1149750a83b8db055f5db0d2@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [+Cc binder maintainers and list] [-Cc lockdep maintainers, USB maintainers, and other random people] On Sat, Dec 02, 2017 at 08:08:01AM -0800, syzbot wrote: > BUG: KASAN: use-after-free in __lock_acquire+0x465e/0x47f0 > kernel/locking/lockdep.c:3378 > Read of size 8 at addr ffff8801cd8e13f0 by task syzkaller236979/3086 > > CPU: 1 PID: 3086 Comm: syzkaller236979 Not tainted 4.15.0-rc1+ #115 > 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 > __lock_acquire+0x465e/0x47f0 kernel/locking/lockdep.c:3378 > lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4004 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:159 > remove_wait_queue+0x81/0x350 kernel/sched/wait.c:50 > ep_remove_wait_queue fs/eventpoll.c:595 [inline] > ep_unregister_pollwait.isra.7+0x18c/0x590 fs/eventpoll.c:613 > ep_free+0x13f/0x320 fs/eventpoll.c:830 > ep_eventpoll_release+0x44/0x60 fs/eventpoll.c:862 > __fput+0x333/0x7f0 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/0x1ae0 kernel/exit.c:865 > do_group_exit+0x149/0x400 kernel/exit.c:968 > SYSC_exit_group kernel/exit.c:979 [inline] > SyS_exit_group+0x1d/0x20 kernel/exit.c:977 > do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] > do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 > entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 > RIP: 0023:0xf7f97c79 > RSP: 002b:00000000ffcb51bc EFLAGS: 00000296 ORIG_RAX: 00000000000000fc > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000080f0298 > RDX: 0000000000000000 RSI: 00000000080d9b18 RDI: 00000000080f02a0 > RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > Allocated by task 3086: > 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:3613 > kmalloc include/linux/slab.h:499 [inline] > kzalloc include/linux/slab.h:688 [inline] > binder_get_thread+0x1cf/0x870 drivers/android/binder.c:4184 > binder_poll+0x8c/0x390 drivers/android/binder.c:4286 > ep_item_poll.isra.10+0xec/0x320 fs/eventpoll.c:884 > ep_insert+0x6a3/0x1b10 fs/eventpoll.c:1455 > SYSC_epoll_ctl fs/eventpoll.c:2106 [inline] > SyS_epoll_ctl+0x12e4/0x1ab0 fs/eventpoll.c:1992 > do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] > do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 > entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 > > Freed by task 3086: > 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:3491 [inline] > kfree+0xca/0x250 mm/slab.c:3806 > binder_free_thread drivers/android/binder.c:4211 [inline] > binder_thread_dec_tmpref+0x27f/0x310 drivers/android/binder.c:1808 > binder_thread_release+0x27d/0x540 drivers/android/binder.c:4275 > binder_ioctl+0xc05/0x141a drivers/android/binder.c:4492 > C_SYSC_ioctl fs/compat_ioctl.c:1473 [inline] > compat_SyS_ioctl+0x151/0x2a30 fs/compat_ioctl.c:1419 > do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] > do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 > entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 This is a bug in the binder driver. binder_poll() tells the poll system to use the wait queue embedded in the 'struct binder_thread', but then the BINDER_THREAD_EXIT ioctl will free the 'struct binder_thread' out from under it. Perhaps either the waitqueue should be associated with the 'struct binder_proc' rather than the 'struct binder_thread', or binder_poll() should take a reference to the 'struct binder_thread'. But I'm not too familiar with binder or epoll, so I don't know which solution is best. Here is a program which reproduces the bug, assuming /dev/binder0 exists: #include #include #include #include #define BINDER_THREAD_EXIT 0x40046208ul int main() { int fd, epfd; struct epoll_event event = { .events = EPOLLIN }; fd = open("/dev/binder0", O_RDONLY); epfd = epoll_create(1000); epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &event); ioctl(fd, BINDER_THREAD_EXIT, NULL); }