commit 45862f9f5ef5d3c9da37f35e4fe4b18618530cfa
author Dennis Sweeney <36520290+sweeneyde@users.noreply.github.com> Mon May 10 05:10:22 2021 -0400
committer GitHub <noreply@github.com> Mon May 10 10:10:22 2021 +0100
tree e4a51d5e8890370304d06f4cb2bfdd375f540098
parent 8e8307d70bb9dc18cfeeed3277c076309b27515e

Prevent access outside buffer (GH-26012)

Python/ceval.c

diff --git a/Python/ceval.c b/Python/ceval.c
index f745067..8e1c5bd 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4794,8 +4794,10 @@
 }
 
 static inline unsigned char *
-skip_to_next_entry(unsigned char *p) {
-    for (; (p[0]&128) == 0; p++);
+skip_to_next_entry(unsigned char *p, unsigned char *end) {
+    while (p < end && ((p[0] & 128) == 0)) {
+        p++;
+    }
     return p;
 }
 
@@ -4863,7 +4865,7 @@
             parse_block(scan, &res);
             return res;
         }
-        scan = skip_to_next_entry(scan);
+        scan = skip_to_next_entry(scan, end);
     }
     res.b_handler = -1;
     return res;