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[FFmpeg-devel,2/5] avcodec/exr: Check limits to avoid overflow in delta computation

Message ID 20201016173530.9142-2-michael@niedermayer.cc
State Accepted
Commit 6910e0f4e5c40b5b902e4dd87256327d860d53f5
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Series [FFmpeg-devel,1/5] avcodec/mobiclip: Avoid signed integer overflows in idct()
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Commit Message

Michael Niedermayer Oct. 16, 2020, 5:35 p.m. UTC
Fixes: signed integer overflow: 553590816 - -2145378049 cannot be represented in type 'int'
Fixes: 26315/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EXR_fuzzer-5938755121446912
Fixes: 26340/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EXR_fuzzer-5644316208529408

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/exr.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)
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Patch

diff --git a/libavcodec/exr.c b/libavcodec/exr.c
index 80117deb8a..cf7824402a 100644
--- a/libavcodec/exr.c
+++ b/libavcodec/exr.c
@@ -1520,15 +1520,27 @@  static int decode_header(EXRContext *s, AVFrame *frame)
             continue;
         } else if ((var_size = check_header_variable(s, "dataWindow", "box2i",
                                                      31)) >= 0) {
+            int xmin, ymin, xmax, ymax;
             if (!var_size) {
                 ret = AVERROR_INVALIDDATA;
                 goto fail;
             }
 
-            s->xmin   = bytestream2_get_le32(&s->gb);
-            s->ymin   = bytestream2_get_le32(&s->gb);
-            s->xmax   = bytestream2_get_le32(&s->gb);
-            s->ymax   = bytestream2_get_le32(&s->gb);
+            xmin   = bytestream2_get_le32(&s->gb);
+            ymin   = bytestream2_get_le32(&s->gb);
+            xmax   = bytestream2_get_le32(&s->gb);
+            ymax   = bytestream2_get_le32(&s->gb);
+
+            if (xmin > xmax || ymin > ymax ||
+                (unsigned)xmax - xmin >= INT_MAX ||
+                (unsigned)ymax - ymin >= INT_MAX) {
+                ret = AVERROR_INVALIDDATA;
+                goto fail;
+            }
+            s->xmin = xmin;
+            s->xmax = xmax;
+            s->ymin = ymin;
+            s->ymax = ymax;
             s->xdelta = (s->xmax - s->xmin) + 1;
             s->ydelta = (s->ymax - s->ymin) + 1;