builtin/mv: don't use memory after free

If 'src' already ends with a slash, then add_slash() will just return
it, meaning that 'free(src_with_slash)' is actually 'free(src)'.  Since
we use 'src' later, this will result in use-after-free.

In fact, this cannot happen because 'src' comes from
internal_copy_pathspec() without the KEEP_TRAILING_SLASH flag, so any
trailing '/' will have been stripped; but static analysis tools are not
clever enough to realise this and so warn that 'src' could be used after
having been free'd.  Fix this by checking that 'src_w_slash' is indeed
newly allocated memory.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/mv.c b/builtin/mv.c
index 21c46d1636e6e87dd9eaaca60ac08ebbbc4efec3..7e26eb5229a0c8a526314cecb9860c3dfb0fed00 100644 (file)
--- a/builtin/mv.c
+++ b/builtin/mv.c
@@ -162,7 +162,8 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
                                        if (strncmp(path, src_w_slash, len_w_slash))
                                                break;
                                }
-                               free((char *)src_w_slash);
+                               if (src_w_slash != src)
+                                       free((char *)src_w_slash);
 
                                if (last - first < 1)
                                        bad = _("source directory is empty");