commit 9fbcb1402efab4e287f25145a69ba14c9c6dbce9
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Tue Nov 13 16:39:36 2018 -0800
committer GitHub <noreply@github.com> Tue Nov 13 16:39:36 2018 -0800
tree 6d38028a96dcc976f1574d4ffb67e09cad4e4eb4
parent c30830bbb2630605b9b7915af7e82c8124e705c2

[3.7] bpo-35214: Fix OOB memory access in unicode escape parser (GH-10506) (GH-10522)



Discovered using clang's MemorySanitizer when it ran python3's
test_fstring test_misformed_unicode_character_name.

An msan build will fail by simply executing: ./python -c 'u"\N"'
(cherry picked from commit 746b2d35ea47005054ed774fecaed64fab803d7d)


Co-authored-by: Gregory P. Smith <greg@krypto.org>


https://bugs.python.org/issue35214

Objects/unicodeobject.c

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index fe833a7..71eb654 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -6042,7 +6042,7 @@
             }
 
             message = "malformed \\N character escape";
-            if (*s == '{') {
+            if (s < end && *s == '{') {
                 const char *start = ++s;
                 size_t namelen;
                 /* look for the closing brace */