Fix use-after-free in awk.

CVE: CVE-2022-30065
Upstream-Status: Submitted [http://lists.busybox.net/pipermail/busybox/2022-June/089768.html]
Signed-off-by: Ross Burton <ross.burton@arm.com>

fixes https://bugs.busybox.net/show_bug.cgi?id=14781

Signed-off-by: Natanael Copa <ncopa at alpinelinux.org>
---
 editors/awk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/editors/awk.c b/editors/awk.c
index 079d0bde5..728ee8685 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -3128,6 +3128,9 @@ static var *evaluate(node *op, var *res)
 
 		case XC( OC_MOVE ):
 			debug_printf_eval("MOVE\n");
+			/* make sure that we never return a temp var */
+			if (L.v == TMPVAR0)
+				L.v = res;
 			/* if source is a temporary string, jusk relink it to dest */
 			if (R.v == TMPVAR1
 			 && !(R.v->type & VF_NUMBER)
-- 
2.36.1