From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754615AbdKINHb (ORCPT ); Thu, 9 Nov 2017 08:07:31 -0500 Received: from mail-oi0-f68.google.com ([209.85.218.68]:49302 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753805AbdKINH3 (ORCPT ); Thu, 9 Nov 2017 08:07:29 -0500 X-Google-Smtp-Source: AGs4zMZPyRotpNpNjkv391GzLGKVGudvA+eEUG9kDhuhZl6BIElDl6ZfLhqvOrR4QnayC98YVjxGVI0Z7vSK4WtHReY= MIME-Version: 1.0 In-Reply-To: <47c1c53ffe47fbd34a3f1aae92391e7ff5a0aab8.1510205498.git.arvind.yadav.cs@gmail.com> References: <47c1c53ffe47fbd34a3f1aae92391e7ff5a0aab8.1510205498.git.arvind.yadav.cs@gmail.com> From: Andrey Konovalov Date: Thu, 9 Nov 2017 14:07:28 +0100 Message-ID: Subject: Re: [RFT] [media] em28xx: Fix use-after-free in v4l2_fh_init To: Arvind Yadav Cc: Mauro Carvalho Chehab , Kostya Serebryany , Dmitry Vyukov , LKML , linux-media@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 9, 2017 at 6:49 AM, Arvind Yadav wrote: > Here, em28xx_free_v4l2 is release "v4l2->dev->v4l2" > Which is allready release by em28xx_v4l2_init. > > Signed-off-by: Arvind Yadav Hi Arvind, I still see the crash with your patch. Thanks! em28xx 1-1:0.0: Disconnecting em28xx 1-1:0.0: Registering V4L2 extension em28xx 1-1:0.0: Config register raw data: 0xffffffed em28xx 1-1:0.0: AC97 chip type couldn't be determined em28xx 1-1:0.0: No AC97 audio processor em28xx 1-1:0.0: failed to create media graph em28xx 1-1:0.0: V4L2 device video0 deregistered em28xx 1-1:0.0: Binding DVB extension ================================================================== BUG: KASAN: use-after-free in v4l2_fh_init+0x239/0x280 Read of size 8 at addr ffff88006b40c998 by task v4l_id/5917 CPU: 0 PID: 5917 Comm: v4l_id Not tainted 4.14.0-rc8-44455-ge2105594a876-dirty #102 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 dump_stack+0xe1/0x157 lib/dump_stack.c:53 print_address_description+0x71/0x234 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 kasan_report+0x173/0x270 mm/kasan/report.c:409 __asan_report_load8_noabort+0x19/0x20 mm/kasan/report.c:430 v4l2_fh_init+0x239/0x280 drivers/media/v4l2-core/v4l2-fh.c:33 v4l2_fh_open+0x76/0xa0 drivers/media/v4l2-core/v4l2-fh.c:70 em28xx_v4l2_open+0x252/0x6f0 drivers/media/usb/em28xx/em28xx-video.c:2060 v4l2_open+0x1b7/0x380 drivers/media/v4l2-core/v4l2-dev.c:425 chrdev_open+0x1db/0x520 fs/char_dev.c:417 do_dentry_open+0x735/0xe20 fs/open.c:752 vfs_open+0x13e/0x230 fs/open.c:866 do_last fs/namei.c:3388 path_openat+0x722/0x2860 fs/namei.c:3528 do_filp_open+0x13f/0x1d0 fs/namei.c:3563 do_sys_open+0x362/0x4c0 fs/open.c:1059 SYSC_open fs/open.c:1077 SyS_open+0x32/0x40 fs/open.c:1072 entry_SYSCALL_64_fastpath+0x23/0xc2 arch/x86/entry/entry_64.S:203 RIP: 0033:0x7faff04be120 RSP: 002b:00007fff4d967aa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000046 RCX: 00007faff04be120 RDX: 00007faff0773138 RSI: 0000000000000000 RDI: 00007fff4d967f1e RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400884 R13: 00007fff4d967c00 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 3170: save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x11a/0x290 mm/slub.c:2773 kmalloc ./include/linux/slab.h:494 kzalloc ./include/linux/slab.h:667 em28xx_v4l2_init+0x10c/0x3660 drivers/media/usb/em28xx/em28xx-video.c:2438 em28xx_init_extension+0x11a/0x190 drivers/media/usb/em28xx/em28xx-core.c:1110 request_module_async+0x6a/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3161 process_one_work+0x925/0x15d0 kernel/workqueue.c:2113 process_scheduled_works kernel/workqueue.c:2173 worker_thread+0x6c0/0x10d0 kernel/workqueue.c:2252 kthread+0x346/0x410 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:432 Freed by task 3170: save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:524 slab_free_hook mm/slub.c:1391 slab_free_freelist_hook mm/slub.c:1413 slab_free mm/slub.c:2989 kfree+0xf2/0x2e0 mm/slub.c:3920 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2025 kref_put ./include/linux/kref.h:70 em28xx_v4l2_init+0x2382/0x3660 drivers/media/usb/em28xx/em28xx-video.c:2788 em28xx_init_extension+0x11a/0x190 drivers/media/usb/em28xx/em28xx-core.c:1110 request_module_async+0x6a/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3161 process_one_work+0x925/0x15d0 kernel/workqueue.c:2113 process_scheduled_works kernel/workqueue.c:2173 worker_thread+0x6c0/0x10d0 kernel/workqueue.c:2252 kthread+0x346/0x410 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:432 The buggy address belongs to the object at ffff88006b40c200 which belongs to the cache kmalloc-8192 of size 8192 The buggy address is located 1944 bytes inside of 8192-byte region [ffff88006b40c200, ffff88006b40e200) The buggy address belongs to the page: page:ffffea0001ad0200 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 flags: 0x100000000008100(slab|head) raw: 0100000000008100 0000000000000000 0000000000000000 0000000180030003 raw: 0000000000000000 0000000100000001 ffff88006c402a80 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88006b40c880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88006b40c900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88006b40c980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88006b40ca00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88006b40ca80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== > --- > This bug report by Andrey Konovalov "net/media/em28xx: use-after-free in v4l2_fh_init" > > drivers/media/usb/em28xx/em28xx-video.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c > index 8d253a5..f1ee53f 100644 > --- a/drivers/media/usb/em28xx/em28xx-video.c > +++ b/drivers/media/usb/em28xx/em28xx-video.c > @@ -2785,8 +2785,8 @@ static int em28xx_v4l2_init(struct em28xx *dev) > v4l2_ctrl_handler_free(&v4l2->ctrl_handler); > v4l2_device_unregister(&v4l2->v4l2_dev); > err: > - dev->v4l2 = NULL; > kref_put(&v4l2->ref, em28xx_free_v4l2); > + dev->v4l2 = NULL; > mutex_unlock(&dev->lock); > return ret; > } > -- > 1.9.1 >