linux-kernel - [PATCH 2/2] kconfig: Deny command substitution in string values

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Date:   Mon, 20 Sep 2021 23:39:57 +0200
From:   Richard Weinberger <richard@....at>
To:     masahiroy@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
        Richard Weinberger <richard@....at>
Subject: [PATCH 2/2] kconfig: Deny command substitution in string values

The post processed .config file will get included in shell
and makefiles. So make sure that a string does not contain
symbols that allow command substitution.
If such a malformed string is found, return empty string
and report it.

Signed-off-by: Richard Weinberger <richard@....at>
---
 scripts/kconfig/symbol.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 4a31bb943f79..1035ecdddc99 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -880,6 +880,11 @@ const char *sym_escape_string(struct symbol *sym)
 
 	in = sym_get_string_value(sym);
 
+	if (strspn(in, "`$")) {
+		fprintf(stderr, "%s: invalid characters in string found\n", sym->name);
+		return xstrdup("\"\"");
+	}
+
 	reslen = strlen(in) + strlen("\"\"") + 1;
 
 	p = in;
-- 
2.26.2