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Commit cb8affb5 authored by David Gstir's avatar David Gstir Committed by Herbert Xu
Browse files

crypto: nx - Fix timing leak in GCM and CCM decryption 



Using non-constant time memcmp() makes the verification of the authentication
tag in the decrypt path vulnerable to timing attacks. Fix this by using
crypto_memneq() instead.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarDavid Gstir <david@sigma-star.at>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 8005c49d

drivers/crypto/nx/nx-aes-ccm.c

+1 −1
Original line number Diff line number Diff line
@@ -409,7 +409,7 @@ static int ccm_nx_decrypt(struct aead_request *req, 
		processed += to_process;

	} while (processed < nbytes);



	rc = memcmp(csbcpb->cpb.aes_ccm.out_pat_or_mac, priv->oauth_tag,

	rc = crypto_memneq(csbcpb->cpb.aes_ccm.out_pat_or_mac, priv->oauth_tag,

		    authsize) ? -EBADMSG : 0;

out:

	spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);

drivers/crypto/nx/nx-aes-gcm.c

+2 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 


#include <crypto/internal/aead.h>

#include <crypto/aes.h>

#include <crypto/algapi.h>

#include <crypto/scatterwalk.h>

#include <linux/module.h>

#include <linux/types.h>
@@ -418,7 +419,7 @@ static int gcm_aes_nx_crypt(struct aead_request *req, int enc, 
			itag, req->src, req->assoclen + nbytes,

			crypto_aead_authsize(crypto_aead_reqtfm(req)),

			SCATTERWALK_FROM_SG);

		rc = memcmp(itag, otag,

		rc = crypto_memneq(itag, otag,

			    crypto_aead_authsize(crypto_aead_reqtfm(req))) ?

		     -EBADMSG : 0;

	}