X-Git-Url: https://git.octo.it/?p=git.git;a=blobdiff_plain;f=patch-delta.c;h=8f318ed8aaf180419f97887501317fc1d2b54c09;hp=26281ea1230f730931442bc0ed59966a6f4031be;hb=HEAD;hpb=b43d44779bf98977b211256f936d0edda8a9625a

diff --git a/patch-delta.c b/patch-delta.c
index 26281ea1..8f318ed8 100644
--- a/patch-delta.c
+++ b/patch-delta.c
@@ -13,8 +13,8 @@
 #include <string.h>
 #include "delta.h"
 
-void *patch_delta(void *src_buf, unsigned long src_size,
-		  void *delta_buf, unsigned long delta_size,
+void *patch_delta(const void *src_buf, unsigned long src_size,
+		  const void *delta_buf, unsigned long delta_size,
 		  unsigned long *dst_size)
 {
 	const unsigned char *data, *top;
@@ -28,45 +28,61 @@ void *patch_delta(void *src_buf, unsigned long src_size,
 	top = delta_buf + delta_size;
 
 	/* make sure the orig file size matches what we expect */
-	size = get_delta_hdr_size(&data);
+	size = get_delta_hdr_size(&data, top);
 	if (size != src_size)
 		return NULL;
 
 	/* now the result size */
-	size = get_delta_hdr_size(&data);
-	dst_buf = malloc(size);
+	size = get_delta_hdr_size(&data, top);
+	dst_buf = malloc(size + 1);
 	if (!dst_buf)
 		return NULL;
+	dst_buf[size] = 0;
 
 	out = dst_buf;
 	while (data < top) {
 		cmd = *data++;
 		if (cmd & 0x80) {
 			unsigned long cp_off = 0, cp_size = 0;
-			const unsigned char *buf;
 			if (cmd & 0x01) cp_off = *data++;
 			if (cmd & 0x02) cp_off |= (*data++ << 8);
 			if (cmd & 0x04) cp_off |= (*data++ << 16);
 			if (cmd & 0x08) cp_off |= (*data++ << 24);
 			if (cmd & 0x10) cp_size = *data++;
 			if (cmd & 0x20) cp_size |= (*data++ << 8);
+			if (cmd & 0x40) cp_size |= (*data++ << 16);
 			if (cp_size == 0) cp_size = 0x10000;
-			buf = (cmd & 0x40) ? dst_buf : src_buf;
-			memcpy(out, buf + cp_off, cp_size);
+			if (cp_off + cp_size < cp_size ||
+			    cp_off + cp_size > src_size ||
+			    cp_size > size)
+				goto bad;
+			memcpy(out, src_buf + cp_off, cp_size);
 			out += cp_size;
-		} else {
+			size -= cp_size;
+		} else if (cmd) {
+			if (cmd > size)
+				goto bad;
 			memcpy(out, data, cmd);
 			out += cmd;
 			data += cmd;
+			size -= cmd;
+		} else {
+			/*
+			 * cmd == 0 is reserved for future encoding
+			 * extensions. In the mean time we must fail when
+			 * encountering them (might be data corruption).
+			 */
+			goto bad;
 		}
 	}
 
 	/* sanity check */
-	if (data != top || out - dst_buf != size) {
+	if (data != top || size != 0) {
+		bad:
 		free(dst_buf);
 		return NULL;
 	}
 
-	*dst_size = size;
+	*dst_size = out - dst_buf;
 	return dst_buf;
 }