Fix buffer overflow in git-grep

If PATH_MAX on your system is smaller than any path stored in the git
repository, that can cause memory corruption inside of the grep_tree
function used by git-grep.

Signed-off-by: Dmitry Potapov <dpotapov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-grep.c b/builtin-grep.c
index ef299108f529fa5fa931d765828f04535c3a6351..647535061c350b68f1583fc12b049a37eb17481c 100644 (file)
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -427,33 +427,35 @@ static int grep_tree(struct grep_opt *opt, const char **paths,
        struct name_entry entry;
        char *down;
        int tn_len = strlen(tree_name);
-       char *path_buf = xmalloc(PATH_MAX + tn_len + 100);
+       struct strbuf pathbuf;
+
+       strbuf_init(&pathbuf, PATH_MAX + tn_len);
 
        if (tn_len) {
-               tn_len = sprintf(path_buf, "%s:", tree_name);
-               down = path_buf + tn_len;
-               strcat(down, base);
-       }
-       else {
-               down = path_buf;
-               strcpy(down, base);
+               strbuf_add(&pathbuf, tree_name, tn_len);
+               strbuf_addch(&pathbuf, ':');
+               tn_len = pathbuf.len;
        }
-       len = strlen(path_buf);
+       strbuf_addstr(&pathbuf, base);
+       len = pathbuf.len;
 
        while (tree_entry(tree, &entry)) {
-               strcpy(path_buf + len, entry.path);
+               int te_len = tree_entry_len(entry.path, entry.sha1);
+               pathbuf.len = len;
+               strbuf_add(&pathbuf, entry.path, te_len);
 
                if (S_ISDIR(entry.mode))
                        /* Match "abc/" against pathspec to
                         * decide if we want to descend into "abc"
                         * directory.
                         */
-                       strcpy(path_buf + len + tree_entry_len(entry.path, entry.sha1), "/");
+                       strbuf_addch(&pathbuf, '/');
 
+               down = pathbuf.buf + tn_len;
                if (!pathspec_matches(paths, down))
                        ;
                else if (S_ISREG(entry.mode))
-                       hit |= grep_sha1(opt, entry.sha1, path_buf, tn_len);
+                       hit |= grep_sha1(opt, entry.sha1, pathbuf.buf, tn_len);
                else if (S_ISDIR(entry.mode)) {
                        enum object_type type;
                        struct tree_desc sub;
@@ -469,6 +471,7 @@ static int grep_tree(struct grep_opt *opt, const char **paths,
                        free(data);
                }
        }
+       strbuf_release(&pathbuf);
        return hit;
 }