From: Zackery Spytz <zspytz@gmail.com>
Date: Wed, 22 Aug 2018 05:54:17 +0000 (-0600)
Subject: [2.7] bpo-34400: Fix more undefined behavior in parsetok.c (GH-8833). (GH-8849)
X-Git-Tag: v2.7.16rc1~174
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb9a1c01d07309006ef5544da62ba813685bd098;p=thirdparty%2FPython%2Fcpython.git

[2.7] bpo-34400: Fix more undefined behavior in parsetok.c (GH-8833). (GH-8849)

(cherry picked from commit 3e26e42c905852394fa136f1cc564dac98b56166)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>
---

diff --git a/Parser/parsetok.c b/Parser/parsetok.c
index 3189873a7a3a..a5e922243c56 100644
--- a/Parser/parsetok.c
+++ b/Parser/parsetok.c
@@ -189,10 +189,12 @@ parsetok(struct tok_state *tok, grammar *g, int start, perrdetail *err_ret,
 
 #ifdef PY_PARSER_REQUIRES_FUTURE_KEYWORD
 #endif
-        if (a >= tok->line_start)
+        if (a != NULL && a >= tok->line_start) {
             col_offset = a - tok->line_start;
-        else
+        }
+        else {
             col_offset = -1;
+        }
 
         if ((err_ret->error =
              PyParser_AddToken(ps, (int)type, str, tok->lineno, col_offset,