[FFmpeg-cvslog] libswscale: avoid UB nullptr-with-offset.
Jeremy Leconte
git at videolan.org
Thu Dec 24 16:34:10 EET 2020
ffmpeg | branch: master | Jeremy Leconte <jleconte at google.com> | Thu Dec 24 04:27:19 2020 +0000| [29cef1bcd6baf4394a24b34bfbec59e97bb3875b] | committer: Michael Niedermayer
libswscale: avoid UB nullptr-with-offset.
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=29cef1bcd6baf4394a24b34bfbec59e97bb3875b
---
libswscale/slice.c | 12 ++++--------
libswscale/swscale_unscaled.c | 4 +---
2 files changed, 5 insertions(+), 11 deletions(-)
diff --git a/libswscale/slice.c b/libswscale/slice.c
index 7849b70f4d..d96db13364 100644
--- a/libswscale/slice.c
+++ b/libswscale/slice.c
@@ -158,14 +158,10 @@ int ff_init_slice_from_src(SwsSlice * s, uint8_t *src[4], int stride[4], int src
chrY + chrH,
lumY + lumH};
- uint8_t *const src_[4] = {src[0] + (relative ? 0 : start[0]) * stride[0],
- src[1] + (relative ? 0 : start[1]) * stride[1],
- src[2] + (relative ? 0 : start[2]) * stride[2],
- src[3] + (relative ? 0 : start[3]) * stride[3]};
-
s->width = srcW;
- for (i = 0; i < 4; ++i) {
+ for (i = 0; i < 4 && src[i] != NULL; ++i) {
+ uint8_t *const src_i = src[i] + (relative ? 0 : start[i]) * stride[i];
int j;
int first = s->plane[i].sliceY;
int n = s->plane[i].available_lines;
@@ -175,13 +171,13 @@ int ff_init_slice_from_src(SwsSlice * s, uint8_t *src[4], int stride[4], int src
if (start[i] >= first && n >= tot_lines) {
s->plane[i].sliceH = FFMAX(tot_lines, s->plane[i].sliceH);
for (j = 0; j < lines; j+= 1)
- s->plane[i].line[start[i] - first + j] = src_[i] + j * stride[i];
+ s->plane[i].line[start[i] - first + j] = src_i + j * stride[i];
} else {
s->plane[i].sliceY = start[i];
lines = lines > n ? n : lines;
s->plane[i].sliceH = lines;
for (j = 0; j < lines; j+= 1)
- s->plane[i].line[j] = src_[i] + j * stride[i];
+ s->plane[i].line[j] = src_i + j * stride[i];
}
}
diff --git a/libswscale/swscale_unscaled.c b/libswscale/swscale_unscaled.c
index 563de39696..7e92f3fafc 100644
--- a/libswscale/swscale_unscaled.c
+++ b/libswscale/swscale_unscaled.c
@@ -1805,7 +1805,7 @@ static int planarCopyWrapper(SwsContext *c, const uint8_t *src[],
const AVPixFmtDescriptor *desc_src = av_pix_fmt_desc_get(c->srcFormat);
const AVPixFmtDescriptor *desc_dst = av_pix_fmt_desc_get(c->dstFormat);
int plane, i, j;
- for (plane = 0; plane < 4; plane++) {
+ for (plane = 0; plane < 4 && dst[plane] != NULL; plane++) {
int length = (plane == 0 || plane == 3) ? c->srcW : AV_CEIL_RSHIFT(c->srcW, c->chrDstHSubSample);
int y = (plane == 0 || plane == 3) ? srcSliceY: AV_CEIL_RSHIFT(srcSliceY, c->chrDstVSubSample);
int height = (plane == 0 || plane == 3) ? srcSliceH: AV_CEIL_RSHIFT(srcSliceH, c->chrDstVSubSample);
@@ -1813,8 +1813,6 @@ static int planarCopyWrapper(SwsContext *c, const uint8_t *src[],
uint8_t *dstPtr = dst[plane] + dstStride[plane] * y;
int shiftonly = plane == 1 || plane == 2 || (!c->srcRange && plane == 0);
- if (!dst[plane])
- continue;
// ignore palette for GRAY8
if (plane == 1 && !dst[2]) continue;
if (!src[plane] || (plane == 1 && !src[2])) {
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