[FFmpeg-devel] [PATCH 2/2] avfilter/signature_lookup: Do not dereference NULL pointers after malloc failure

[Michael Niedermayer <michael@niedermayer.cc>]

Fixes: CID 1403229 Dereference after null check

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavfilter/signature_lookup.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/libavfilter/signature_lookup.c b/libavfilter/signature_lookup.c
index 86dd0c66754..6e45fde1b5a 100644
--- a/libavfilter/signature_lookup.c
+++ b/libavfilter/signature_lookup.c
@@ -37,6 +37,14 @@
 #define STATUS_END_REACHED 1
 #define STATUS_BEGIN_REACHED 2
 
+static void sll_free(MatchingInfo **sll)
+{
+    while (*sll) {
+        sll = &(*sll)->next;
+        av_freep(sll);
+    }
+}
+
 static void fill_l1distlut(uint8_t lut[])
 {
     int i, j, tmp_i, tmp_j,count;
@@ -290,6 +298,10 @@ static MatchingInfo* get_matching_parameters(AVFilterContext *ctx, SignatureCont
                             av_log(ctx, AV_LOG_FATAL, "Could not allocate memory");
                         c = c->next;
                     }
+                    if (!c) {
+                        sll_free(&cands);
+                        goto error;
+                    }
                     c->framerateratio = (i+1.0) / 30;
                     c->score = hspace[i][j].score;
                     c->offset = j-90;
@@ -305,6 +317,7 @@ static MatchingInfo* get_matching_parameters(AVFilterContext *ctx, SignatureCont
             }
         }
     }
+    error:
     for (i = 0; i < MAX_FRAMERATE; i++) {
         av_freep(&hspace[i]);
     }
@@ -520,16 +533,6 @@ static MatchingInfo evaluate_parameters(AVFilterContext *ctx, SignatureContext *
     return bestmatch;
 }
 
-static void sll_free(MatchingInfo *sll)
-{
-    void *tmp;
-    while (sll) {
-        tmp = sll;
-        sll = sll->next;
-        av_freep(&tmp);
-    }
-}
-
 static MatchingInfo lookup_signatures(AVFilterContext *ctx, SignatureContext *sc, StreamContext *first, StreamContext *second, int mode)
 {
     CoarseSignature *cs, *cs2;
@@ -572,7 +575,7 @@ static MatchingInfo lookup_signatures(AVFilterContext *ctx, SignatureContext *sc
                    "ratio %f, offset %d, score %d, %d frames matching\n",
                    bestmatch.first->index, bestmatch.second->index,
                    bestmatch.framerateratio, bestmatch.offset, bestmatch.score, bestmatch.matchframes);
-            sll_free(infos);
+            sll_free(&infos);
         }
     } while (find_next_coarsecandidate(sc, second->coarsesiglist, &cs, &cs2, 0) && !bestmatch.whole);
     return bestmatch;
-- 
2.17.1

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