To prevent timing attacks, HMAC value comparison needs to be constant
time. Replace the memcmp() with the correct function, crypto_memneq().
Fixes: f67cf491175a ("thunderbolt: Add support for Internal Connection Manager (ICM)")
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
drivers/thunderbolt/domain.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c
index 45239703745e5..7e0eb3c07f1c7 100644
--- a/drivers/thunderbolt/domain.c
+++ b/drivers/thunderbolt/domain.c
@@ -11,10 +11,11 @@
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <crypto/hash.h>
+#include <crypto/utils.h>
#include "tb.h"
static DEFINE_IDA(tb_domain_ida);
@@ -746,11 +747,11 @@ int tb_domain_challenge_switch_key(struct tb *tb, struct tb_switch *sw)
ret = crypto_shash_digest(shash, challenge, sizeof(hmac), hmac);
if (ret)
goto err_free_shash;
/* The returned HMAC must match the one we calculated */
- if (memcmp(response, hmac, sizeof(hmac))) {
+ if (crypto_memneq(response, hmac, sizeof(hmac))) {
ret = -EKEYREJECTED;
goto err_free_shash;
}
crypto_free_shash(tfm);
--
2.50.1
