[CVE-2016-10713] Fix out-of-bounds access to lines in a patch

This bug can trigger with malformed patches.
* src/pch.c (pch_write_line): Avoid out-of-bounds access to
p_line[line][p_len[line] - 1] when p_len[line] is 0.

Change-Id: I9e82bc52555b7de139535280fe96d1a31d196176
Signed-off-by: JinWang An <jinwang.an@samsung.com>

diff --git a/src/pch.c b/src/pch.c
index f958b1924b46f56c109e535f07973463ebaa275d..0d7769c40460c658059a5deeabdcde61614fdb79 100644 (file)
--- a/src/pch.c
+++ b/src/pch.c
@@ -2243,7 +2243,7 @@ pfetch (lin line)
 bool
 pch_write_line (lin line, FILE *file)
 {
-  bool after_newline = p_line[line][p_len[line] - 1] == '\n';
+  bool after_newline = (p_len[line] > 0) && (p_line[line][p_len[line] - 1] == '\n');
   if (! fwrite (p_line[line], sizeof (*p_line[line]), p_len[line], file))
     write_fatal ();
   return after_newline;