From 539e66891279044d2ade4e9d2590939301c5944c Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Fri, 17 Apr 2020 16:51:44 -0700
Subject: patch: fix out of bounds memory access.

On empty lines, we'd read one byte before the start of the buffer.
---
 toys/posix/patch.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'toys/posix')

diff --git a/toys/posix/patch.c b/toys/posix/patch.c
index d3d77792..f0caf8ae 100644
--- a/toys/posix/patch.c
+++ b/toys/posix/patch.c
@@ -327,7 +327,7 @@ void patch_main(void)
     // Other versions of patch accept damaged patches, so we need to also.
     if (strip || !patchlinenum++) {
       int len = strlen(patchline);
-      if (patchline[len-1] == '\r') {
+      if (len && patchline[len-1] == '\r') {
         if (!strip && !FLAG(s)) fprintf(stderr, "Removing DOS newlines\n");
         strip = 1;
         patchline[len-1]=0;
-- 
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