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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
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