upstream: produce a useful error message if the user's shell is set

incorrectly during "match exec" processing. bz#2791 reported by Dario
Bertini; ok dtucker

OpenBSD-Commit-ID: cf9eddd6a6be726cb73bd9c3936f3888cd85c03d

1 files changed, 6 insertions, 1 deletions

diff --git a/readconf.c b/readconf.c
index 27b535e1f..d1b7871ec 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.307 2019/06/28 13:35:04 deraadt Exp $ */
+/* $OpenBSD: readconf.c,v 1.308 2019/08/09 05:05:54 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -486,6 +486,11 @@ execute_in_shell(const char *cmd)
         if ((shell = getenv("SHELL")) == NULL)
                 shell = _PATH_BSHELL;
 
+        if (access(shell, X_OK) == -1) {
+                fatal("Shell \"%s\" is not executable: %s",
+                    shell, strerror(errno));
+        }
+
         /* Need this to redirect subprocess stdin/out */
         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1)
                 fatal("open(/dev/null): %s", strerror(errno));