setup_git_directory: make sure GIT_DIR is a valid repository.

diff --git a/update-index.c b/update-index.c
index 5bbc3de2898caddfd019fac77c6a1daf922250cf..11b7f6a5169e0a9a957155c03c7a56667efe980c 100644 (file)
--- a/update-index.c
+++ b/update-index.c
@@ -338,7 +338,7 @@ static void read_index_info(int line_termination)
        struct strbuf buf;
        strbuf_init(&buf);
        while (1) {
-               char *ptr;
+               char *ptr, *tab;
                char *path_name;
                unsigned char sha1[20];
                unsigned int mode;
@@ -348,12 +348,15 @@ static void read_index_info(int line_termination)
                        break;
 
                mode = strtoul(buf.buf, &ptr, 8);
-               if (ptr == buf.buf || *ptr != ' ' ||
-                   get_sha1_hex(ptr + 1, sha1) ||
-                   ptr[41] != '\t')
+               if (ptr == buf.buf || *ptr != ' ')
                        goto bad_line;
 
-               ptr += 42;
+               tab = strchr(ptr, '\t');
+               if (!tab || tab - ptr < 41)
+                       goto bad_line;
+               if (get_sha1_hex(tab - 40, sha1) || tab[-41] != ' ')
+                       goto bad_line;
+               ptr = tab + 1;
 
                if (line_termination && ptr[0] == '"')
                        path_name = unquote_c_style(ptr, NULL);