[patch libspamc] avoid NULL deref

[Frederik Deweerdt]

Hi,

When calling message_dump with a NULL m argument, m is checked against
being NULL before calling message write, but m is derefenced in the
libspamc_log call below.

The patch below just returns if 'm' is NULL.

Regards,
Frederik

diff --git a/spamc/libspamc.c b/spamc/libspamc.c
index 12e5048..7f6fd11 100644
--- a/spamc/libspamc.c
+++ b/spamc/libspamc.c
@@ -853,9 +853,14 @@ void message_dump(int in_fd, int out_fd, struct message *m)
     char buf[8196];
     int bytes;
 
-    if (m != NULL && m->type != MESSAGE_NONE) {
+    if (m == NULL) {
+       return;
+    }
+
+    if (m->type != MESSAGE_NONE) {
        message_write(out_fd, m);
     }
+
     while ((bytes = full_read(in_fd, 1, buf, 8192, 8192)) > 0) {
        if (bytes != full_write(out_fd, 1, buf, bytes)) {
            libspamc_log(m->priv->flags, LOG_ERR, "oops! message_dump of %d 
returned different",