From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mga02.intel.com ([134.134.136.20]:6730 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752194AbcKHQHZ (ORCPT ); Tue, 8 Nov 2016 11:07:25 -0500 From: Sakari Ailus To: linux-media@vger.kernel.org Cc: hverkuil@xs4all.nl Subject: [PATCH v2 1/1] v4l: compat: Prevent allocating excessive amounts of memory Date: Tue, 8 Nov 2016 18:06:44 +0200 Message-Id: <1478621204-26905-1-git-send-email-sakari.ailus@linux.intel.com> Sender: linux-media-owner@vger.kernel.org List-ID: get_v4l2_ext_controls32() is used to convert the 32-bit compat struct into native 64-bit representation. The function multiplies the array length by the entry length before validating size. Perform the size validation first. Also use unsigned values for size computation. Make similar changes to get_v4l2_buffer32() for multi-plane buffers. Signed-off-by: Sakari Ailus --- since v1: - Use unsigned loop variables. - Count from zero upwards rather than downwards until zero. drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 30 +++++++++++++++------------ 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c index bacecbd..eac9565 100644 --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c @@ -409,7 +409,6 @@ static int get_v4l2_buffer32(struct v4l2_buffer *kp, struct v4l2_buffer32 __user struct v4l2_plane32 __user *uplane32; struct v4l2_plane __user *uplane; compat_caddr_t p; - int num_planes; int ret; if (!access_ok(VERIFY_READ, up, sizeof(struct v4l2_buffer32)) || @@ -429,12 +428,15 @@ static int get_v4l2_buffer32(struct v4l2_buffer *kp, struct v4l2_buffer32 __user return -EFAULT; if (V4L2_TYPE_IS_MULTIPLANAR(kp->type)) { - num_planes = kp->length; - if (num_planes == 0) { + unsigned int num_planes; + + if (kp->length == 0) { kp->m.planes = NULL; /* num_planes == 0 is legal, e.g. when userspace doesn't * need planes array on DQBUF*/ return 0; + } else if (kp->length > VIDEO_MAX_PLANES) { + return -EINVAL; } if (get_user(p, &up->m.planes)) @@ -442,16 +444,16 @@ static int get_v4l2_buffer32(struct v4l2_buffer *kp, struct v4l2_buffer32 __user uplane32 = compat_ptr(p); if (!access_ok(VERIFY_READ, uplane32, - num_planes * sizeof(struct v4l2_plane32))) + kp->length * sizeof(struct v4l2_plane32))) return -EFAULT; /* We don't really care if userspace decides to kill itself * by passing a very big num_planes value */ - uplane = compat_alloc_user_space(num_planes * - sizeof(struct v4l2_plane)); + uplane = compat_alloc_user_space(kp->length * + sizeof(struct v4l2_plane)); kp->m.planes = (__force struct v4l2_plane *)uplane; - while (--num_planes >= 0) { + for (num_planes = 0; num_planes < kp->length; num_planes++) { ret = get_v4l2_plane32(uplane, uplane32, kp->memory); if (ret) return ret; @@ -665,7 +667,7 @@ static int get_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext { struct v4l2_ext_control32 __user *ucontrols; struct v4l2_ext_control __user *kcontrols; - int n; + unsigned int n; compat_caddr_t p; if (!access_ok(VERIFY_READ, up, sizeof(struct v4l2_ext_controls32)) || @@ -675,20 +677,22 @@ static int get_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext copy_from_user(kp->reserved, up->reserved, sizeof(kp->reserved))) return -EFAULT; - n = kp->count; - if (n == 0) { + if (kp->count == 0) { kp->controls = NULL; return 0; + } else if (kp->count > V4L2_CID_MAX_CTRLS) { + return -EINVAL; } if (get_user(p, &up->controls)) return -EFAULT; ucontrols = compat_ptr(p); if (!access_ok(VERIFY_READ, ucontrols, - n * sizeof(struct v4l2_ext_control32))) + kp->count * sizeof(struct v4l2_ext_control32))) return -EFAULT; - kcontrols = compat_alloc_user_space(n * sizeof(struct v4l2_ext_control)); + kcontrols = compat_alloc_user_space(kp->count * + sizeof(struct v4l2_ext_control)); kp->controls = (__force struct v4l2_ext_control *)kcontrols; - while (--n >= 0) { + for (n = 0; n < kp->count; n++) { u32 id; if (copy_in_user(kcontrols, ucontrols, sizeof(*ucontrols))) -- 2.7.4