From 4e801463c7d2b26de747d3684cf75b722b0594af Mon Sep 17 00:00:00 2001
From: "Juan F. Codagnone" <jcodagnone@gmail.com>
Date: Wed, 24 Jan 2018 13:56:47 -0300
Subject: mailinfo: avoid segfault when can't open files

If <msg> or <patch> files can't be opened, then mailinfo() returns an
error before it even initializes mi->p_hdr_data or mi->s_hdr_data.
When cmd_mailinfo() then calls clear_mailinfo(), we dereference the
NULL pointers trying to free their contents.

Signed-off-by: Juan F. Codagnone <jcodagnone@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/mailinfo.c b/mailinfo.c
index a489d9d..36ec927 100644
--- a/mailinfo.c
+++ b/mailinfo.c
@@ -1149,11 +1149,13 @@ void clear_mailinfo(struct mailinfo *mi)
 	strbuf_release(&mi->inbody_header_accum);
 	free(mi->message_id);
 
-	for (i = 0; mi->p_hdr_data[i]; i++)
-		strbuf_release(mi->p_hdr_data[i]);
+	if (mi->p_hdr_data)
+		for (i = 0; mi->p_hdr_data[i]; i++)
+			strbuf_release(mi->p_hdr_data[i]);
 	free(mi->p_hdr_data);
-	for (i = 0; mi->s_hdr_data[i]; i++)
-		strbuf_release(mi->s_hdr_data[i]);
+	if (mi->s_hdr_data)
+		for (i = 0; mi->s_hdr_data[i]; i++)
+			strbuf_release(mi->s_hdr_data[i]);
 	free(mi->s_hdr_data);
 
 	while (mi->content < mi->content_top) {
-- 
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