Reject $SHELL if it is not a full path.

2 files changed, 4 insertions, 2 deletions

diff --git a/tmux.c b/tmux.c
index 196edf6c..5d4fda72 100644
--- a/tmux.c
+++ b/tmux.c
@@ -98,7 +98,9 @@ getshell(void)
 int
 checkshell(const char *shell)
 {
-	if (shell == NULL || *shell == '\0' || areshell(shell))
+	if (shell == NULL || *shell == '\0' || *shell != '/')
+		return (0);
+	if (areshell(shell))
 		return (0);
 	if (access(shell, X_OK) != 0)
 		return (0);
diff --git a/window.c b/window.c
index 0736daeb..4f55c513 100644
--- a/window.c
+++ b/window.c
@@ -697,7 +697,7 @@ window_pane_spawn(struct window_pane *wp, const char *cmd, const char *shell,
 		if (*wp->cmd != '\0') {
 			/* Set SHELL but only if it is currently not useful. */
 			shell = getenv("SHELL");
-			if (shell == NULL || *shell == '\0' || areshell(shell))
+			if (checkshell(shell))
 				setenv("SHELL", wp->shell, 1);
 
 			execl(_PATH_BSHELL, "sh", "-c", wp->cmd, (char *) NULL);