From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Sun, 15 Oct 2017 19:29:01 +0000 (+0200)
Subject: wg: encoding: be more paranoid
X-Git-Tag: v1.0.20191226~204
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7fe7f81088d9ff3fb392c12ca970e79cc78e1061;p=thirdparty%2Fwireguard-tools.git

wg: encoding: be more paranoid

Needless, but overkill can be fun.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

diff --git a/src/encoding.c b/src/encoding.c
index 3d5e94b..c407b57 100644
--- a/src/encoding.c
+++ b/src/encoding.c
@@ -102,10 +102,10 @@ bool key_from_hex(uint8_t key[static WG_KEY_LEN], const char *hex)
 
 bool key_is_zero(const uint8_t key[static WG_KEY_LEN])
 {
-	uint8_t acc = 0;
+	volatile uint8_t acc = 0;
 	for (unsigned int i = 0; i < WG_KEY_LEN; ++i) {
 		acc |= key[i];
 		__asm__ ("" : "=r" (acc) : "0" (acc));
 	}
-	return acc == 0;
+	return 1 & ((acc - 1) >> 8);
 }