From: Eli Zaretskii <eliz@gnu.org>
Date: Tue, 25 Jul 2023 17:38:01 +0000 (+0300)
Subject: Avoid crashes under 'which-key-mode'
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=65834b8f8d53402517da7fe2446f5bac0aa30c39;p=emacs.git

Avoid crashes under 'which-key-mode'

* src/keyboard.c (Fthis_single_command_keys): Don't allow calls to
Fvector with negative first argument.  (Bug#64857)
---

diff --git a/src/keyboard.c b/src/keyboard.c
index 41cda2e65de..2e850b74b9b 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -11138,8 +11138,8 @@ the command loop or by `read-key-sequence'.
 The value is always a vector.  */)
   (void)
 {
-  return Fvector (this_command_key_count
-		  - this_single_command_key_start,
+  ptrdiff_t nkeys = this_command_key_count - this_single_command_key_start;
+  return Fvector (nkeys < 0 ? 0 : nkeys,
 		  (XVECTOR (this_command_keys)->contents
 		   + this_single_command_key_start));
 }