[PATCH 1/2] crypto: keembay - use crypto_memneq() to compare GCM AEAD tags
"David C.C.M. Gall" <[email protected]>
| Newsgroups | org.kernel.vger.linux-crypto,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
Use crypto_memneq() for constant-time comparison. The GCM path in keembay-ocs-aes-core.c verifes the received authentication tag with memcmp(), which returns early on the first mismatched byte. This leaks valid-prefix length and allows for valid tag forgery which violates the INT-CTXT guarantee of AEAD. Assisted-by: gregkh_clanker_t1000 Signed-off-by: David C.C.M. Gall <[email protected]> --- drivers/crypto/intel/keembay/keembay-ocs-aes-core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/crypto/intel/keembay/keembay-ocs-aes-core.c b/drivers/crypto/intel/keembay/keembay-ocs-aes-core.c index 8a8f6c81e010..f8f4517ccad0 100644 --- a/drivers/crypto/intel/keembay/keembay-ocs-aes-core.c +++ b/drivers/crypto/intel/keembay/keembay-ocs-aes-core.c @@ -11,6 +11,7 @@ #include <crypto/internal/aead.h> #include <crypto/internal/skcipher.h> #include <crypto/scatterwalk.h> +#include <crypto/utils.h> #include <linux/clk.h> #include <linux/completion.h> #include <linux/dma-mapping.h> @@ -919,7 +920,7 @@ static int kmb_ocs_aead_run(struct aead_request *req) /* For GCM decrypt, we have to compare in_tag with out_tag. */ if (rctx->instruction == OCS_DECRYPT) { - rc = memcmp(rctx->in_tag, rctx->out_tag, tag_size) ? + rc = crypto_memneq(rctx->in_tag, rctx->out_tag, tag_size) ? -EBADMSG : 0; goto exit; } -- 2.43.0