Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752998Ab3JSQIX (ORCPT ); Sat, 19 Oct 2013 12:08:23 -0400 Received: from mail-lb0-f178.google.com ([209.85.217.178]:50034 "EHLO mail-lb0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750961Ab3JSQIV (ORCPT ); Sat, 19 Oct 2013 12:08:21 -0400 From: Ricardo Ribalda To: Kyungmin Park , Sylwester Nawrocki , Mauro Carvalho Chehab , Kukjin Kim , Pawel Osciak , Marek Szyprowski , linux-media@vger.kernel.org (open list:SAMSUNG S5P/EXYNO...), linux-arm-kernel@lists.infradead.org (moderated list:ARM/S5P EXYNOS AR...), linux-samsung-soc@vger.kernel.org (moderated list:ARM/S5P EXYNOS AR...), linux-kernel@vger.kernel.org (open list) Cc: Ricardo Ribalda Subject: [PATCH v2] videobuf2: Add missing lock held on vb2_fop_relase Date: Sat, 19 Oct 2013 18:07:57 +0200 Message-Id: <1382198877-27164-1-git-send-email-ricardo.ribalda@gmail.com> X-Mailer: git-send-email 1.8.3.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6950 Lines: 171 vb2_fop_relase does not held the lock although it is modifying the queue->owner field. This could lead to race conditions on the vb2_perform_io function when multiple applications are accessing the video device via read/write API: [ 308.297741] BUG: unable to handle kernel NULL pointer dereference at 0000000000000260 [ 308.297759] IP: [] vb2_perform_fileio+0x372/0x610 [videobuf2_core] [ 308.297794] PGD 159719067 PUD 158119067 PMD 0 [ 308.297812] Oops: 0000 #1 SMP [ 308.297826] Modules linked in: qt5023_video videobuf2_dma_sg qtec_xform videobuf2_vmalloc videobuf2_memops videobuf2_core qtec_white qtec_mem gpio_xilinx qtec_cmosis qtec_pcie fglrx(PO) spi_xilinx spi_bitbang qt5023 [ 308.297888] CPU: 1 PID: 2189 Comm: java Tainted: P O 3.11.0-qtec-standard #1 [ 308.297919] Hardware name: QTechnology QT5022/QT5022, BIOS PM_2.1.0.309 X64 05/23/2013 [ 308.297952] task: ffff8801564e1690 ti: ffff88014dc02000 task.ti: ffff88014dc02000 [ 308.297962] RIP: 0010:[] [] vb2_perform_fileio+0x372/0x610 [videobuf2_core] [ 308.297985] RSP: 0018:ffff88014dc03df8 EFLAGS: 00010202 [ 308.297995] RAX: 0000000000000000 RBX: ffff880158a23000 RCX: dead000000100100 [ 308.298003] RDX: 0000000000000000 RSI: dead000000200200 RDI: 0000000000000000 [ 308.298012] RBP: ffff88014dc03e58 R08: 0000000000000000 R09: 0000000000000001 [ 308.298020] R10: ffffea00051e8380 R11: ffff88014dc03fd8 R12: ffff880158a23070 [ 308.298029] R13: ffff8801549040b8 R14: 0000000000198000 R15: 0000000001887e60 [ 308.298040] FS: 00007f65130d5700(0000) GS:ffff88015ed00000(0000) knlGS:0000000000000000 [ 308.298049] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 308.298057] CR2: 0000000000000260 CR3: 0000000159630000 CR4: 00000000000007e0 [ 308.298064] Stack: [ 308.298071] ffff880156416c00 0000000000198000 0000000000000000 ffff880100000001 [ 308.298087] ffff88014dc03f50 00000000810a79ca 0002000000000001 ffff880154904718 [ 308.298101] ffff880156416c00 0000000000198000 ffff880154904338 ffff88014dc03f50 [ 308.298116] Call Trace: [ 308.298143] [] vb2_read+0x14/0x20 [videobuf2_core] [ 308.298198] [] vb2_fop_read+0xc4/0x120 [videobuf2_core] [ 308.298252] [] v4l2_read+0x7e/0xc0 [ 308.298296] [] vfs_read+0xa9/0x160 [ 308.298312] [] SyS_read+0x52/0xb0 [ 308.298328] [] tracesys+0xd0/0xd5 [ 308.298335] Code: e5 d6 ff ff 83 3d be 24 00 00 04 89 c2 4c 8b 45 b0 44 8b 4d b8 0f 8f 20 02 00 00 85 d2 75 32 83 83 78 03 00 00 01 4b 8b 44 c5 48 <8b> 88 60 02 00 00 85 c9 0f 84 b0 00 00 00 8b 40 58 89 c2 41 89 [ 308.298487] RIP [] vb2_perform_fileio+0x372/0x610 [videobuf2_core] [ 308.298507] RSP [ 308.298514] CR2: 0000000000000260 [ 308.298526] ---[ end trace e8f01717c96d1e41 ]--- v2: Add bug found by Sylvester Nawrocki fimc-capture and fimc-lite where calling vb2_fop_release with the lock held. Therefore a new __vb2_fop_release function has been created to be used by drivers that overload the release function. Signed-off-by: Ricardo Ribalda --- drivers/media/platform/exynos4-is/fimc-capture.c | 2 +- drivers/media/platform/exynos4-is/fimc-lite.c | 2 +- drivers/media/usb/em28xx/em28xx-video.c | 2 +- drivers/media/v4l2-core/videobuf2-core.c | 18 +++++++++++++++++- include/media/videobuf2-core.h | 2 ++ 5 files changed, 22 insertions(+), 4 deletions(-) diff --git a/drivers/media/platform/exynos4-is/fimc-capture.c b/drivers/media/platform/exynos4-is/fimc-capture.c index fb27ff7..c38d247c 100644 --- a/drivers/media/platform/exynos4-is/fimc-capture.c +++ b/drivers/media/platform/exynos4-is/fimc-capture.c @@ -549,7 +549,7 @@ static int fimc_capture_release(struct file *file) vc->streaming = false; } - ret = vb2_fop_release(file); + ret = __vb2_fop_release(file, true); if (close) { clear_bit(ST_CAPT_BUSY, &fimc->state); diff --git a/drivers/media/platform/exynos4-is/fimc-lite.c b/drivers/media/platform/exynos4-is/fimc-lite.c index e5798f7..021d804 100644 --- a/drivers/media/platform/exynos4-is/fimc-lite.c +++ b/drivers/media/platform/exynos4-is/fimc-lite.c @@ -546,7 +546,7 @@ static int fimc_lite_release(struct file *file) mutex_unlock(&entity->parent->graph_mutex); } - vb2_fop_release(file); + __vb2_fop_release(file, true); pm_runtime_put(&fimc->pdev->dev); clear_bit(ST_FLITE_SUSPENDED, &fimc->state); diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c index 9d10334..6a5c147 100644 --- a/drivers/media/usb/em28xx/em28xx-video.c +++ b/drivers/media/usb/em28xx/em28xx-video.c @@ -1664,7 +1664,7 @@ static int em28xx_v4l2_close(struct file *filp) em28xx_videodbg("users=%d\n", dev->users); mutex_lock(&dev->lock); - vb2_fop_release(filp); + __vb2_fop_release(filp, false); if (dev->users == 1) { /* the device is already disconnect, diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 594c75e..ce309a8 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -2619,16 +2619,32 @@ int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma) } EXPORT_SYMBOL_GPL(vb2_fop_mmap); -int vb2_fop_release(struct file *file) +int __vb2_fop_release(struct file *file, bool lock_is_held) { struct video_device *vdev = video_devdata(file); + struct mutex *lock; if (file->private_data == vdev->queue->owner) { + if (lock_is_held) + lock = NULL; + else + lock = vdev->queue->lock ? + vdev->queue->lock : vdev->lock; + if (lock) + mutex_lock(lock); vb2_queue_release(vdev->queue); vdev->queue->owner = NULL; + if (lock) + mutex_unlock(lock); } return v4l2_fh_release(file); } +EXPORT_SYMBOL_GPL(__vb2_fop_release); + +int vb2_fop_release(struct file *file) +{ + return __vb2_fop_release(file, false); +} EXPORT_SYMBOL_GPL(vb2_fop_release); ssize_t vb2_fop_write(struct file *file, char __user *buf, diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index 6781258..cd1e4d5 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -491,6 +491,8 @@ int vb2_ioctl_expbuf(struct file *file, void *priv, int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma); int vb2_fop_release(struct file *file); +/* must be used if the lock is held. */ +int __vb2_fop_release(struct file *file, bool lock_is_held); ssize_t vb2_fop_write(struct file *file, char __user *buf, size_t count, loff_t *ppos); ssize_t vb2_fop_read(struct file *file, char __user *buf, -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/