gnu: libwebp: Fix CVE-2016-9085.

* gnu/packages/patches/libwebp-CVE-2016-9085.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/image.scm (libwebp)[source]: Use it.

gnu/local.mk

@@ -663,6 +663,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/libunwind-CVE-2015-3239.patch		\
   %D%/packages/patches/libupnp-CVE-2016-6255.patch		\
   %D%/packages/patches/libvpx-CVE-2016-2818.patch		\
+  %D%/packages/patches/libwebp-CVE-2016-9085.patch		\
   %D%/packages/patches/libwmf-CAN-2004-0941.patch		\
   %D%/packages/patches/libwmf-CVE-2006-3376.patch		\
   %D%/packages/patches/libwmf-CVE-2007-0455.patch		\

gnu/packages/image.scm

@@ -676,6 +676,7 @@ multi-dimensional image processing.")
        (uri (string-append
              "http://downloads.webmproject.org/releases/webp/libwebp-" version
              ".tar.gz"))
+       (patches (search-patches "libwebp-CVE-2016-9085.patch"))
        (sha256
         (base32
          "1pqki1g8nzi8qgciysypd5r38zccv81np1dn43g27830rmpnrmka"))))

gnu/packages/patches/libwebp-CVE-2016-9085.patch

@@ -0,0 +1,144 @@
+Fix CVE-2016-9085 (several integer overflows):
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-9085
+http://seclists.org/oss-sec/2016/q4/253
+
+Patch copied from upstream source repository:
+
+https://chromium.googlesource.com/webm/libwebp/+/e2affacc35f1df6cc3b1a9fa0ceff5ce2d0cce83
+
+From e2affacc35f1df6cc3b1a9fa0ceff5ce2d0cce83 Mon Sep 17 00:00:00 2001
+From: Pascal Massimino <pascal.massimino@gmail.com>
+Date: Mon, 10 Oct 2016 11:48:39 +0200
+Subject: [PATCH] fix potential overflow when width * height * 4 >= (1<<32)
+
+Mostly: avoid doing calculation like: ptr + j * stride
+when stride is 'int'. Rather use size_t, or pointer increments (ptr += stride)
+when possible.
+
+BUG=webp:314
+
+Change-Id: I81c684b515dd1ec4f601f32d50a6e821c4e46e20
+---
+ examples/gifdec.c | 56 +++++++++++++++++++++++++++++++------------------------
+ 1 file changed, 32 insertions(+), 24 deletions(-)
+
+diff --git a/examples/gifdec.c b/examples/gifdec.c
+index 83c3d82..7df176f 100644
+--- a/examples/gifdec.c
++++ b/examples/gifdec.c
+@@ -20,6 +20,7 @@
+ 
+ #include "webp/encode.h"
+ #include "webp/mux_types.h"
++#include "webp/format_constants.h"
+ 
+ #define GIF_TRANSPARENT_COLOR 0x00000000
+ #define GIF_WHITE_COLOR       0xffffffff
+@@ -103,12 +104,19 @@ int GIFReadFrame(GifFileType* const gif, int transparent_index,
+   const GifImageDesc* const image_desc = &gif->Image;
+   uint32_t* dst = NULL;
+   uint8_t* tmp = NULL;
+-  int ok = 0;
+-  GIFFrameRect rect = {
++  const GIFFrameRect rect = {
+       image_desc->Left, image_desc->Top, image_desc->Width, image_desc->Height
+   };
++  const uint64_t memory_needed = 4 * rect.width * (uint64_t)rect.height;
++  int ok = 0;
+   *gif_rect = rect;
+ 
++  if (memory_needed != (size_t)memory_needed ||
++      memory_needed > 4 * MAX_IMAGE_AREA) {
++    fprintf(stderr, "Image is too large (%d x %d).", rect.width, rect.height);
++    return 0;
++  }
++
+   // Use a view for the sub-picture:
+   if (!WebPPictureView(picture, rect.x_offset, rect.y_offset,
+                        rect.width, rect.height, &sub_image)) {
+@@ -132,15 +140,15 @@ int GIFReadFrame(GifFileType* const gif, int transparent_index,
+            y += interlace_jumps[pass]) {
+         if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;
+         Remap(gif, tmp, rect.width, transparent_index,
+-              dst + y * sub_image.argb_stride);
++              dst + y * (size_t)sub_image.argb_stride);
+       }
+     }
+   } else {  // Non-interlaced image.
+     int y;
+-    for (y = 0; y < rect.height; ++y) {
++    uint32_t* ptr = dst;
++    for (y = 0; y < rect.height; ++y, ptr += sub_image.argb_stride) {
+       if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;
+-      Remap(gif, tmp, rect.width, transparent_index,
+-            dst + y * sub_image.argb_stride);
++      Remap(gif, tmp, rect.width, transparent_index, ptr);
+     }
+   }
+   ok = 1;
+@@ -216,13 +224,11 @@ int GIFReadMetadata(GifFileType* const gif, GifByteType** const buf,
+ 
+ static void ClearRectangle(WebPPicture* const picture,
+                            int left, int top, int width, int height) {
+-  int j;
+-  for (j = top; j < top + height; ++j) {
+-    uint32_t* const dst = picture->argb + j * picture->argb_stride;
+-    int i;
+-    for (i = left; i < left + width; ++i) {
+-      dst[i] = GIF_TRANSPARENT_COLOR;
+-    }
++  int i, j;
++  const size_t stride = picture->argb_stride;
++  uint32_t* dst = picture->argb + top * stride + left;
++  for (j = 0; j < height; ++j, dst += stride) {
++    for (i = 0; i < width; ++i) dst[i] = GIF_TRANSPARENT_COLOR;
+   }
+ }
+ 
+@@ -246,29 +252,31 @@ void GIFDisposeFrame(GIFDisposeMethod dispose, const GIFFrameRect* const rect,
+   if (dispose == GIF_DISPOSE_BACKGROUND) {
+     GIFClearPic(curr_canvas, rect);
+   } else if (dispose == GIF_DISPOSE_RESTORE_PREVIOUS) {
+-    const int src_stride = prev_canvas->argb_stride;
+-    const uint32_t* const src =
+-        prev_canvas->argb + rect->x_offset + rect->y_offset * src_stride;
+-    const int dst_stride = curr_canvas->argb_stride;
+-    uint32_t* const dst =
+-        curr_canvas->argb + rect->x_offset + rect->y_offset * dst_stride;
++    const size_t src_stride = prev_canvas->argb_stride;
++    const uint32_t* const src = prev_canvas->argb + rect->x_offset
++                              + rect->y_offset * src_stride;
++    const size_t dst_stride = curr_canvas->argb_stride;
++    uint32_t* const dst = curr_canvas->argb + rect->x_offset
++                        + rect->y_offset * dst_stride;
+     assert(prev_canvas != NULL);
+-    WebPCopyPlane((uint8_t*)src, 4 * src_stride, (uint8_t*)dst, 4 * dst_stride,
++    WebPCopyPlane((uint8_t*)src, (int)(4 * src_stride),
++                  (uint8_t*)dst, (int)(4 * dst_stride),
+                   4 * rect->width, rect->height);
+   }
+ }
+ 
+ void GIFBlendFrames(const WebPPicture* const src,
+                     const GIFFrameRect* const rect, WebPPicture* const dst) {
+-  int j;
++  int i, j;
++  const size_t src_stride = src->argb_stride;
++  const size_t dst_stride = dst->argb_stride;
+   assert(src->width == dst->width && src->height == dst->height);
+   for (j = rect->y_offset; j < rect->y_offset + rect->height; ++j) {
+-    int i;
+     for (i = rect->x_offset; i < rect->x_offset + rect->width; ++i) {
+-      const uint32_t src_pixel = src->argb[j * src->argb_stride + i];
++      const uint32_t src_pixel = src->argb[j * src_stride + i];
+       const int src_alpha = src_pixel >> 24;
+       if (src_alpha != 0) {
+-        dst->argb[j * dst->argb_stride + i] = src_pixel;
++        dst->argb[j * dst_stride + i] = src_pixel;
+       }
+     }
+   }
+-- 
+2.10.1
+