Avoid a potential buffer overflow in backslash escaping.

https://github.com/onetrueawk/awk/issues/121

diff --git a/usr.bin/awk/b.c b/usr.bin/awk/b.c
index 53418e1..e3c45e9 100644 (file)
--- a/usr.bin/awk/b.c
+++ b/usr.bin/awk/b.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: b.c,v 1.36 2021/03/02 20:41:42 millert Exp $  */
+/*     $OpenBSD: b.c,v 1.37 2021/07/08 21:26:39 millert Exp $  */
 /****************************************************************
 Copyright (C) Lucent Technologies 1997
 All Rights Reserved
@@ -1108,7 +1108,7 @@ rescan:
                                         * program to track each string's length.
                                         */
                                        for (i = 1; i <= UCHAR_MAX; i++) {
-                                               if (!adjbuf((char **) &buf, &bufsz, bp-buf+1, 100, (char **) &bp, "relex2"))
+                                               if (!adjbuf((char **) &buf, &bufsz, bp-buf+2, 100, (char **) &bp, "relex2"))
                                                    FATAL("out of space for reg expr %.10s...", lastre);
                                                if (cc->cc_func(i)) {
                                                        /* escape backslash */