Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755922AbbDUPdc (ORCPT ); Tue, 21 Apr 2015 11:33:32 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:57288 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755896AbbDUPd1 (ORCPT ); Tue, 21 Apr 2015 11:33:27 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Tadeusz Struk , Stephan Mueller , Herbert Xu , Luis Henriques Subject: [PATCH 3.16.y-ckt 047/144] crypto: aesni - fix memory usage in GCM decryption Date: Tue, 21 Apr 2015 16:30:32 +0100 Message-Id: <1429630329-21748-48-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1429630329-21748-1-git-send-email-luis.henriques@canonical.com> References: <1429630329-21748-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3029 Lines: 70 3.16.7-ckt10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephan Mueller commit ccfe8c3f7e52ae83155cb038753f4c75b774ca8a upstream. The kernel crypto API logic requires the caller to provide the length of (ciphertext || authentication tag) as cryptlen for the AEAD decryption operation. Thus, the cipher implementation must calculate the size of the plaintext output itself and cannot simply use cryptlen. The RFC4106 GCM decryption operation tries to overwrite cryptlen memory in req->dst. As the destination buffer for decryption only needs to hold the plaintext memory but cryptlen references the input buffer holding (ciphertext || authentication tag), the assumption of the destination buffer length in RFC4106 GCM operation leads to a too large size. This patch simply uses the already calculated plaintext size. In addition, this patch fixes the offset calculation of the AAD buffer pointer: as mentioned before, cryptlen already includes the size of the tag. Thus, the tag does not need to be added. With the addition, the AAD will be written beyond the already allocated buffer. Note, this fixes a kernel crash that can be triggered from user space via AF_ALG(aead) -- simply use the libkcapi test application from [1] and update it to use rfc4106-gcm-aes. Using [1], the changes were tested using CAVS vectors to demonstrate that the crypto operation still delivers the right results. [1] http://www.chronox.de/libkcapi.html CC: Tadeusz Struk Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu Signed-off-by: Luis Henriques --- arch/x86/crypto/aesni-intel_glue.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c index 6dfb7d0b139a..6d4fabac779c 100644 --- a/arch/x86/crypto/aesni-intel_glue.c +++ b/arch/x86/crypto/aesni-intel_glue.c @@ -1109,7 +1109,7 @@ static int __driver_rfc4106_decrypt(struct aead_request *req) src = kmalloc(req->cryptlen + req->assoclen, GFP_ATOMIC); if (!src) return -ENOMEM; - assoc = (src + req->cryptlen + auth_tag_len); + assoc = (src + req->cryptlen); scatterwalk_map_and_copy(src, req->src, 0, req->cryptlen, 0); scatterwalk_map_and_copy(assoc, req->assoc, 0, req->assoclen, 0); @@ -1134,7 +1134,7 @@ static int __driver_rfc4106_decrypt(struct aead_request *req) scatterwalk_done(&src_sg_walk, 0, 0); scatterwalk_done(&assoc_sg_walk, 0, 0); } else { - scatterwalk_map_and_copy(dst, req->dst, 0, req->cryptlen, 1); + scatterwalk_map_and_copy(dst, req->dst, 0, tempCipherLen, 1); kfree(src); } return retval; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/