commit ce3c913909746aa1d782ed8bca5076a656422931
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Sun Oct 06 05:37:20 2019 -0700
committer GitHub <noreply@github.com> Sun Oct 06 05:37:20 2019 -0700
tree b57c0de43e2676b9572598ce64e3adce6fdce10d
parent dc191245d8f63f5ab41afff0468b7463a07e7b00

bpo-38383: Fix possible integer overflow in startswith() of bytes and bytearray. (GH-16603)

(cherry picked from commit 24ddd9c2d6ab61cbce7e68d6de36d4df9bd2c3fb)

Co-authored-by: Hai Shi <shihai1992@gmail.com>

Objects/bytes_methods.c

diff --git a/Objects/bytes_methods.c b/Objects/bytes_methods.c
index 37c5f7d..7d13184 100644
--- a/Objects/bytes_methods.c
+++ b/Objects/bytes_methods.c
@@ -743,7 +743,7 @@
 
     if (direction < 0) {
         /* startswith */
-        if (start + slen > len)
+        if (start > len - slen)
             goto notfound;
     } else {
         /* endswith */