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spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org smtp.helo=fraxinus.osuosl.org; x-aligned-from=fail; x-google-dkim=fail (message has been altered; 2048-bit rsa key) header.d=1e100.net header.i=@1e100.net header.b=pwzl3oRQ; x-ptr=fail x-ptr-helo=fraxinus.osuosl.org x-ptr-lookup=smtp4.osuosl.org; x-return-mx=pass smtp.domain=linuxdriverproject.org smtp.result=pass smtp_is_org_domain=yes header.domain=gmail.com header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128 X-Remote-Delivered-To: driverdev-devel@osuosl.org X-Google-Smtp-Source: AH8x226QV7t1iFnRnGQuMyA4cPimwlnGWn8cHYZv/r4UiVIMlTZp9mhawp1uEQbVKm+zAnSJ6cy1+w== Date: Tue, 30 Jan 2018 13:07:31 -0800 From: Eric Biggers To: syzbot Subject: Re: binder epoll bug (was KASAN: use-after-free Read in __lock_acquire (2)) Message-ID: <20180130210731.yrnbutfv6lhdbmbj@gmail.com> References: <001a1147c73265e0a2055e43711e@google.com> <001a1149750a83b8db055f5db0d2@google.com> <20171213000517.GB62138@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20171213000517.GB62138@gmail.com> User-Agent: NeoMutt/20170609 (1.8.3) X-BeenThere: driverdev-devel@linuxdriverproject.org X-Mailman-Version: 2.1.24 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devel@driverdev.osuosl.org, tkjos@android.com, gregkh@linuxfoundation.org, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org, arve@android.com, maco@android.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, Dec 12, 2017 at 04:05:17PM -0800, Eric Biggers wrote: > [+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); > } No longer occurring on linux-next, probably fixed by the following commit: #syz fix: ANDROID: binder: remove waitqueue when thread exits. _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel