From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Wed, 3 Jan 2018 18:48:52 +0000 (+0000)
Subject: bisect: fix a regression causing a segfault
X-Git-Tag: v2.16.0-rc2~7^2
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/2e9fdc795cb27725e6dda7f4ba78ec0d9553b36a

bisect: fix a regression causing a segfault

In 7c117184d7 ("bisect: fix off-by-one error in
`best_bisection_sorted()`", 2017-11-05) the more careful logic dealing
with freeing p->next in 50e62a8e70 ("rev-list: implement
--bisect-all", 2007-10-22) was removed.

Restore the more careful check to avoid segfaulting. Ideally this
would come with a test case, but we don't have steps to reproduce
this, only a backtrace from gdb pointing to this being the issue.

Reported-by: Yasushi SHOJI <yasushi.shoji@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Acked-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

diff --git a/bisect.c b/bisect.c
index 3756f127b0..87e4dee16d 100644
--- a/bisect.c
+++ b/bisect.c
@@ -229,8 +229,10 @@ static struct commit_list *best_bisection_sorted(struct commit_list *list, int n
 		if (i < cnt - 1)
 			p = p->next;
 	}
-	free_commit_list(p->next);
-	p->next = NULL;
+	if (p) {
+		free_commit_list(p->next);
+		p->next = NULL;
+	}
 	strbuf_release(&buf);
 	free(array);
 	return list;