Re: [PATCH 2/2] Make hash-object more robust against malformed objects

On Sat, Feb 12, 2011 at 12:42:21PM +0100, Thomas Rast wrote:

This patch makes t9350 fail under valgrind:

expecting success: 

        TAG=$(git hash-object -t tag -w tag-content) &&
        git update-ref refs/tags/sonnenschein $TAG &&
        git fast-export -C -C --signed-tags=strip --all > output &&
        test $(grep -c "^tag " output) = 4 &&
        ! grep "Unspecified Tagger" output &&
        git fast-export -C -C --signed-tags=strip --all \
                --fake-missing-tagger > output &&
        test $(grep -c "^tag " output) = 4 &&
        grep "Unspecified Tagger" output


==2862== Invalid read of size 1
==2862==    at 0x4F0C34: prefixcmp (strbuf.c:9)
==2862==    by 0x4F4FB3: parse_tag_buffer (tag.c:109)

Nice. Does this fix it?

--8<--

diff --git a/tag.c b/tag.c
index ecf7c1e..9318ae5 100644
--- a/tag.c
+++ b/tag.c

@@ -97,7 +97,9 @@ int parse_tag_buffer(struct tag *item, const void *data, unsigned long size)
 		item->tagged = NULL;
 	}
 
-	if (prefixcmp(bufptr, "tag "))
+	if (bufptr + 5 < tail && !prefixcmp(bufptr, "tag "))
+		; 		/* good */
+	else
 		return -1;
 	bufptr += 4;
 	nl = memchr(bufptr, '\n', tail - bufptr);

@@ -106,7 +108,7 @@ int parse_tag_buffer(struct tag *item, const void *data, unsigned long size)
 	item->tag = xmemdupz(bufptr, nl - bufptr);
 	bufptr = nl + 1;
 
-	if (!prefixcmp(bufptr, "tagger "))
+	if (bufptr + 8 < tail && !prefixcmp(bufptr, "tagger "))
 		item->date = parse_tag_date(bufptr, tail);
 	else
 		item->date = 0;
--8<--

-- 
Duy