mac80211: use constant time comparison with keys

Otherwise we risk leaking information via timing side channel.

Fixes: fdf7cb4185b6 ("mac80211: accept key reinstall without changing anything")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index ae995c8480db9639e1070a6f4743f1e6d6213e81..035d16fe926e81f6a0dfde3a4fb6b10d22d62527 100644 (file)
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -19,6 +19,7 @@
 #include <linux/slab.h>
 #include <linux/export.h>
 #include <net/mac80211.h>
+#include <crypto/algapi.h>
 #include <asm/unaligned.h>
 #include "ieee80211_i.h"
 #include "driver-ops.h"
@@ -635,7 +636,7 @@ int ieee80211_key_link(struct ieee80211_key *key,
         * new version of the key to avoid nonce reuse or replay issues.
         */
        if (old_key && key->conf.keylen == old_key->conf.keylen &&
-           !memcmp(key->conf.key, old_key->conf.key, key->conf.keylen)) {
+           !crypto_memneq(key->conf.key, old_key->conf.key, key->conf.keylen)) {
                ieee80211_key_free_unused(key);
                ret = 0;
                goto out;