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[FFmpeg-devel,2/2] avcodec/dirac_vlc: Fix undefined shift

Message ID 20170719004430.6747-2-michael@niedermayer.cc
State Accepted
Commit 69e7daf6ce2a5893936ba18572c58180b29d67f9
Headers show

Commit Message

Michael Niedermayer July 19, 2017, 12:44 a.m. UTC 
Fixes: runtime error: shift exponent 64 is too large for 64-bit type 'residual' (aka 'unsigned long')
Fixes: 2674/clusterfuzz-testcase-minimized-4999700518273024

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/dirac_vlc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
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Patch

diff --git a/libavcodec/dirac_vlc.c b/libavcodec/dirac_vlc.c
index 336d22a182..773f720858 100644
--- a/libavcodec/dirac_vlc.c
+++ b/libavcodec/dirac_vlc.c
@@ -216,9 +216,14 @@  static void generate_offset_lut(DiracGolombLUT *lut, int off)
         INIT_RESIDUE(res);
         SET_RESIDUE(res, idx, LUT_BITS);
 
-        l->preamble      = CONVERT_TO_RESIDUE(res >> (RSIZE_BITS - off), off);
         l->preamble_bits = off;
-        l->sign = ((l->preamble >> (RSIZE_BITS - l->preamble_bits)) & 1) ? -1 : +1;
+        if (off) {
+            l->preamble  = CONVERT_TO_RESIDUE(res >> (RSIZE_BITS - off), off);
+            l->sign      = ((l->preamble >> (RSIZE_BITS - l->preamble_bits)) & 1) ? -1 : +1;
+        } else {
+            l->preamble  = 0;
+            l->sign = 1;
+        }
 
         search_for_golomb(l, res << off, LUT_BITS - off);
     }