[FFmpeg-cvslog] avcodec/pixlet: Avoid signed integer overflow in scaling in filterfn()

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Mon Oct 26 21:30:19 2020 +0100| [ab70bfcbdd23916b9ee975197c387ed8f1897395] | committer: Michael Niedermayer

avcodec/pixlet: Avoid signed integer overflow in scaling in filterfn()

Fixes: signed integer overflow: 11494 * 1073741824000000 cannot be represented in type 'long'
Fixes: 26586/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PIXLET_fuzzer-5752633970917376

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 0c1f20c6c858b753effda274b58ef635d1924915)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ab70bfcbdd23916b9ee975197c387ed8f1897395
---

 libavcodec/pixlet.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/pixlet.c b/libavcodec/pixlet.c
index 6cb6516227..937076b126 100644
--- a/libavcodec/pixlet.c
+++ b/libavcodec/pixlet.c
@@ -404,7 +404,7 @@ static void filterfn(int16_t *dest, int16_t *tmp, unsigned size, int64_t scale)
                 (int64_t) low [i - 1] * -INT64_C(325392907)  +
                 (int64_t) high[i + 0] *  INT64_C(1518500249) +
                 (int64_t) high[i - 1] *  INT64_C(1518500249);
-        dest[i * 2] = av_clip_int16(((value >> 32) * scale) >> 32);
+        dest[i * 2] = av_clip_int16(((value >> 32) * (uint64_t)scale) >> 32);
     }
 
     for (i = 0; i < hsize; i++) {
@@ -415,7 +415,7 @@ static void filterfn(int16_t *dest, int16_t *tmp, unsigned size, int64_t scale)
                 (int64_t) high[i + 1] *  INT64_C(303700064)  +
                 (int64_t) high[i + 0] * -INT64_C(3644400640) +
                 (int64_t) high[i - 1] *  INT64_C(303700064);
-        dest[i * 2 + 1] = av_clip_int16(((value >> 32) * scale) >> 32);
+        dest[i * 2 + 1] = av_clip_int16(((value >> 32) * (uint64_t)scale) >> 32);
     }
 }