[vlc-commits] stream: do not pass NULL buffer to access module

[Rémi Denis-Courmont]

vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Tue Feb  7 19:56:46 2017 +0200| [dc513b6d375d85cb07e95918bfe965d59410bd81] | committer: Rémi Denis-Courmont

stream: do not pass NULL buffer to access module

access_t.pf_read did not expect a NULL output pointer before the merge
of access_t and stream_t. For files, this caused an EFAULT error, but
for other input types, it would likely crash.

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=dc513b6d375d85cb07e95918bfe965d59410bd81
---

 src/input/stream.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/input/stream.c b/src/input/stream.c
index 7138280..f63ca1f 100644
--- a/src/input/stream.c
+++ b/src/input/stream.c
@@ -364,7 +364,16 @@ static ssize_t vlc_stream_ReadRaw(stream_t *s, void *buf, size_t len)
     if (s->pf_read != NULL)
     {
         assert(priv->block == NULL);
-        ret = s->pf_read(s, buf, len);
+        if (buf == NULL)
+        {
+            if (unlikely(len == 0))
+                return 0;
+
+            char dummy[(len <= 256 ? len : 256)];
+            ret = s->pf_read(s, dummy, sizeof (dummy));
+        }
+        else
+            ret = s->pf_read(s, buf, len);
         return ret;
     }
 
@@ -395,6 +404,7 @@ ssize_t vlc_stream_ReadPartial(stream_t *s, void *buf, size_t len)
     if (ret >= 0)
     {
         priv->offset += ret;
+        assert(ret <= (ssize_t)len);
         return ret;
     }
 
@@ -403,6 +413,7 @@ ssize_t vlc_stream_ReadPartial(stream_t *s, void *buf, size_t len)
         priv->offset += ret;
     if (ret == 0)
         priv->eof = len != 0;
+    assert(ret <= (ssize_t)len);
     return ret;
 }
 
@@ -420,6 +431,7 @@ ssize_t vlc_stream_Read(stream_t *s, void *buf, size_t len)
 
         if (buf != NULL)
             buf = (char *)buf + ret;
+        assert(len >= (size_t)ret);
         len -= ret;
         copied += ret;
     }