Merge branch 'jc/verify-loose-object-header' into maint

Codepaths that read from an on-disk loose object were too loose in
validating what they are reading is a proper object file and
sometimes read past the data they read from the disk, which has
been corrected.  H/t to Gustavo Grieco for reporting.

* jc/verify-loose-object-header:
  unpack_sha1_header(): detect malformed object header
  streaming: make sure to notice corrupt object

diff --git a/sha1_file.c b/sha1_file.c
index 3045aea..7a4f8f8 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1572,7 +1572,9 @@ unsigned long unpack_object_header_buffer(const unsigned char *buf,
        return used;
 }
 
-int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
+static int unpack_sha1_short_header(git_zstream *stream,
+                                   unsigned char *map, unsigned long mapsize,
+                                   void *buffer, unsigned long bufsiz)
 {
        /* Get the data stream */
        memset(stream, 0, sizeof(*stream));
@@ -1585,13 +1587,31 @@ int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long ma
        return git_inflate(stream, 0);
 }
 
+int unpack_sha1_header(git_zstream *stream,
+                      unsigned char *map, unsigned long mapsize,
+                      void *buffer, unsigned long bufsiz)
+{
+       int status = unpack_sha1_short_header(stream, map, mapsize,
+                                             buffer, bufsiz);
+
+       if (status < Z_OK)
+               return status;
+
+       /* Make sure we have the terminating NUL */
+       if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
+               return -1;
+       return 0;
+}
+
 static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
                                        unsigned long mapsize, void *buffer,
                                        unsigned long bufsiz, struct strbuf *header)
 {
        int status;
 
-       status = unpack_sha1_header(stream, map, mapsize, buffer, bufsiz);
+       status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
+       if (status < Z_OK)
+               return -1;
 
        /*
         * Check if entire header is unpacked in the first iteration.
@@ -1682,6 +1702,8 @@ static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
         */
        for (;;) {
                char c = *hdr++;
+               if (!c)
+                       return -1;
                if (c == ' ')
                        break;
                type_len++;

diff --git a/streaming.c b/streaming.c
index 811fcc2..90feec9 100644 (file)
--- a/streaming.c
+++ b/streaming.c
@@ -337,17 +337,17 @@ static open_method_decl(loose)
        st->u.loose.mapped = map_sha1_file(sha1, &st->u.loose.mapsize);
        if (!st->u.loose.mapped)
                return -1;
-       if (unpack_sha1_header(&st->z,
-                              st->u.loose.mapped,
-                              st->u.loose.mapsize,
-                              st->u.loose.hdr,
-                              sizeof(st->u.loose.hdr)) < 0) {
+       if ((unpack_sha1_header(&st->z,
+                               st->u.loose.mapped,
+                               st->u.loose.mapsize,
+                               st->u.loose.hdr,
+                               sizeof(st->u.loose.hdr)) < 0) ||
+           (parse_sha1_header(st->u.loose.hdr, &st->size) < 0)) {
                git_inflate_end(&st->z);
                munmap(st->u.loose.mapped, st->u.loose.mapsize);
                return -1;
        }
 
-       parse_sha1_header(st->u.loose.hdr, &st->size);
        st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
        st->u.loose.hdr_avail = st->z.total_out;
        st->z_state = z_used;