fix potential buffer underflow read in deb_extractor

2 files changed, 7 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 82c4262..1a2fb98 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,7 +3,8 @@ Sun Oct 15 19:36:41 CEST 2017
         Fix potential assign-after-free (on IPC error handling path).
         Make sure to only pass "unsigned char" to functions like isspace().
         Avoid malloc(0) in DEB extractor under certain conditions.
-        Properly initialize 'duration' in ffmpeg extractor. -CG
+        Properly initialize 'duration' in ffmpeg extractor.
+        Fix potential buffer underflow read in DEB extractor. -CG
 
 Fri Oct 13 12:30:37 CEST 2017
         Properly check read error in NSF plugin (from signedness confusion) found by Leon Zhao. -CG
diff --git a/src/plugins/deb_extractor.c b/src/plugins/deb_extractor.c
index afbe8bb..2eb0028 100644
--- a/src/plugins/deb_extractor.c
+++ b/src/plugins/deb_extractor.c
@@ -365,6 +365,8 @@ processControlTGZ (struct EXTRACTOR_ExtractContext *ec,
     return 0;
   if (0 == size)
     return 0;
+  if (size < 4)
+    return 0;
   if (NULL == (cdata = malloc (size)))
     return 0;
   off = 0;
@@ -375,7 +377,9 @@ processControlTGZ (struct EXTRACTOR_ExtractContext *ec,
           free (cdata);
           return 0;
         }
-      memcpy (&cdata[off], data, sret);
+      memcpy (&cdata[off],
+              data,
+              sret);
       off += sret;
     }
   bufSize = cdata[size - 4] + (cdata[size - 3] << 8) + (cdata[size - 2] << 16) + (cdata[size - 1] << 24);