Fix buffer overflow in prepare_attr_stack

If PATH_MAX on your system is smaller than a path stored in the git repo,
it may cause the buffer overflow in prepare_attr_stack.

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

diff --git a/attr.c b/attr.c
index 0fb47d34346ca96addde5cb3722fa5e586057285..17f6a4dca521d9690377f2e93a0192d8a874d2ad 100644 (file)
--- a/attr.c
+++ b/attr.c
@@ -459,7 +459,9 @@ static void prepare_attr_stack(const char *path, int dirlen)
 {
        struct attr_stack *elem, *info;
        int len;
-       char pathbuf[PATH_MAX];
+       struct strbuf pathbuf;
+
+       strbuf_init(&pathbuf, dirlen+2+strlen(GITATTRIBUTES_FILE));
 
        /*
         * At the bottom of the attribute stack is the built-in
@@ -510,13 +512,14 @@ static void prepare_attr_stack(const char *path, int dirlen)
                        len = strlen(attr_stack->origin);
                        if (dirlen <= len)
                                break;
-                       memcpy(pathbuf, path, dirlen);
-                       memcpy(pathbuf + dirlen, "/", 2);
-                       cp = strchr(pathbuf + len + 1, '/');
+                       strbuf_reset(&pathbuf);
+                       strbuf_add(&pathbuf, path, dirlen);
+                       strbuf_addch(&pathbuf, '/');
+                       cp = strchr(pathbuf.buf + len + 1, '/');
                        strcpy(cp + 1, GITATTRIBUTES_FILE);
-                       elem = read_attr(pathbuf, 0);
+                       elem = read_attr(pathbuf.buf, 0);
                        *cp = '\0';
-                       elem->origin = strdup(pathbuf);
+                       elem->origin = strdup(pathbuf.buf);
                        elem->prev = attr_stack;
                        attr_stack = elem;
                        debug_push(elem);