From 3da78400eafcccb97e2f2fd4b227ea40d794ede8 Mon Sep 17 00:00:00 2001

From: Sergey Poznyakoff <gray@gnu.org>

Date: Sat, 11 Feb 2023 11:57:39 +0200

Subject: [PATCH] Fix boundary checking in base-256 decoder

* src/list.c (from_header): Base-256 encoding is at least 2 bytes

long.

---

 src/list.c | 5 +++--

 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/list.c b/src/list.c

index 9fafc425..86bcfdd1 100644

--- a/src/list.c

+++ b/src/list.c

@@ -881,8 +881,9 @@ from_header (char const *where0, size_t digs, char const *type,

 	  where++;

 	}

     }

-  else if (*where == '\200' /* positive base-256 */

-	   || *where == '\377' /* negative base-256 */)

+  else if (where <= lim - 2

+	   && (*where == '\200' /* positive base-256 */

+	       || *where == '\377' /* negative base-256 */))

     {

       /* Parse base-256 output.  A nonnegative number N is

 	 represented as (256**DIGS)/2 + N; a negative number -N is

-- 

2.38.1