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[PATCH] Fix delta integer overflows




From: Martin Koegler <martin.koegler@xxxxxxxxx>

The current delta code produces incorrect pack objects for files > 4GB.

Signed-off-by: Martin Koegler <martin.koegler@xxxxxxxxx>
---
 diff-delta.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

Just pass any file > 4 GB to the delta-compression [by increasing the delta limits].
As file size, a truncated 32bit value will be encoded, leading to broken pack files.

diff --git a/diff-delta.c b/diff-delta.c
index 3797ce6..13e5a01 100644
--- a/diff-delta.c
+++ b/diff-delta.c
@@ -319,7 +319,8 @@ create_delta(const struct delta_index *index,
 	     const void *trg_buf, unsigned long trg_size,
 	     unsigned long *delta_size, unsigned long max_size)
 {
-	unsigned int i, outpos, outsize, moff, msize, val;
+	unsigned int i, val;
+	unsigned long l, outpos, outsize, moff, msize;
 	int inscnt;
 	const unsigned char *ref_data, *ref_top, *data, *top;
 	unsigned char *out;
@@ -336,20 +337,20 @@ create_delta(const struct delta_index *index,
 		return NULL;
 
 	/* store reference buffer size */
-	i = index->src_size;
-	while (i >= 0x80) {
-		out[outpos++] = i | 0x80;
-		i >>= 7;
+	l = index->src_size;
+	while (l >= 0x80) {
+		out[outpos++] = l | 0x80;
+		l >>= 7;
 	}
-	out[outpos++] = i;
+	out[outpos++] = l;
 
 	/* store target buffer size */
-	i = trg_size;
-	while (i >= 0x80) {
-		out[outpos++] = i | 0x80;
-		i >>= 7;
+	l = trg_size;
+	while (l >= 0x80) {
+		out[outpos++] = l | 0x80;
+		l >>= 7;
 	}
-	out[outpos++] = i;
+	out[outpos++] = l;
 
 	ref_data = index->src_buf;
 	ref_top = ref_data + index->src_size;
-- 
2.1.4