[FFmpeg-cvslog] avcodec/pgxdec: Check depth more completely

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Oct  8 21:19:14 2020 +0200| [389b9e9b4f680ff2f7a957559ab6f4edfd94f6ae] | committer: Michael Niedermayer

avcodec/pgxdec: Check depth more completely

Fixes: shift exponent -1 is negative
Fixes: 26107/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PGX_fuzzer-5378790047612928

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=389b9e9b4f680ff2f7a957559ab6f4edfd94f6ae
---

 libavcodec/pgxdec.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/pgxdec.c b/libavcodec/pgxdec.c
index 150f8bbf66..5c735894ab 100644
--- a/libavcodec/pgxdec.c
+++ b/libavcodec/pgxdec.c
@@ -133,14 +133,14 @@ static int pgx_decode_frame(AVCodecContext *avctx, void *data,
     if ((ret = ff_set_dimensions(avctx, width, height)) < 0)
         return ret;
 
-    if (depth <= 8) {
+    if (depth > 0 && depth <= 8) {
         avctx->pix_fmt = AV_PIX_FMT_GRAY8;
         bpp = 8;
-    } else if (depth <= 16) {
+    } else if (depth > 0 && depth <= 16) {
         avctx->pix_fmt = AV_PIX_FMT_GRAY16;
         bpp = 16;
     } else {
-        av_log(avctx, AV_LOG_ERROR, "Maximum depth of 16 bits supported.\n");
+        av_log(avctx, AV_LOG_ERROR, "depth %d is invalid or unsupported.\n", depth);
         return AVERROR_PATCHWELCOME;
     }
     if (bytestream2_get_bytes_left(&g) < width * height * (bpp >> 3))