Avoid buffer overflow when checking for hunk header

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/merge2.c b/merge2.c
index d87b89c765ddf490cba5ca0f2f966a0c7898ce62..dc495afdf94d9c7b623ff54c81fb675b43f4f444 100644 (file)
--- a/merge2.c
+++ b/merge2.c
@@ -347,7 +347,8 @@ struct ci make_merger(struct file af, struct file bf, struct file cf,
                         * align with an end-of-line in 'a', so adjust endpoint
                         */
                        int newa = csl1[c1].a;
-                       if (bf.list[b].start && bf.list[b].start[0] == '\0') {
+                       if (b < bf.elcnt && bf.list[b].start
+                           && bf.list[b].start[0] == '\0') {
                                while (newa > a &&
                                       !ends_line(af.list[newa-1]))
                                        newa--;