From nobody Sat Jul 25 03:21:25 2026 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A66FC823DD; Mon, 20 Jul 2026 03:23:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784517839; cv=none; b=UebNAzgCSPRZIrFGCJni1cpNy5uIO2erUjeoY/kxyxGk4JfzEnz2LDR5ZukgSgGKXq90BUAfqvU076b+4x72aiosUnRarnZ2AqJbGclg7tfc8/fbpgIqBkYViZXfzXTaNVAdzGHOiN9n90No4BHuzEpOqmEgqxBlycMoDQAW3lQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784517839; c=relaxed/simple; bh=HclbTRxz0ynQQF1hk7P/4WcTT6IygMru1qymKWT+8dk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=TWpda7Q9nvIkP6peGmCxR9KT+ZPe5PEx57w/03m2EpwsrwUiUrqC+hqeEdGhq5+nZxjP3aMrUpmKFz67ewiz7zqFplz2wRViP/0cbcMyLRdhc1YUlAuo0UGtKuUUKcNqAVNy2sUXVIVUO0pnBYMBOfXXXAaSiL6MSaZEl27FFM8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: 6db7080883ea11f1aa26b74ffac11d73-20260720 X-CTIC-Tags: HR_CC_COUNT, HR_CC_DOMAIN_COUNT, HR_CC_NAME, HR_CC_NO_NAME, HR_CTE_8B HR_CTT_MISS, HR_DATE_H, HR_DATE_WKD, HR_DATE_ZONE, HR_FROM_NAME HR_SJ_DIGIT_LEN, HR_SJ_LANG, HR_SJ_LEN, HR_SJ_LETTER, HR_SJ_NOR_SYM HR_SJ_PHRASE, HR_SJ_PHRASE_LEN, HR_SJ_WS, HR_TO_COUNT, HR_TO_DOMAIN_COUNT HR_TO_NO_NAME, IP_TRUSTED, SRC_TRUSTED, DN_TRUSTED, SA_EXISTED SN_EXISTED, SPF_NOPASS, DKIM_NOPASS, DMARC_NOPASS, CIE_GOOD CIE_GOOD_SPF, GTI_FG_BS, GTI_RG_INFO, GTI_C_BU, AMN_GOOD ABX_MISS_RDNS X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.12,REQID:bc4c2c07-fa89-4e57-a3e8-68b73ec13b1b,IP:15, URL:0,TC:0,Content:36,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTIO N:release,TS:51 X-CID-INFO: VERSION:1.3.12,REQID:bc4c2c07-fa89-4e57-a3e8-68b73ec13b1b,IP:15,UR L:0,TC:0,Content:36,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:51 X-CID-META: VersionHash:e7bac3a,CLOUDID:d06adba27bd548a630ad98b051b67433,BulkI D:26072011235163SGHVAC,BulkQuantity:0,Recheck:0,SF:10|38|66|78|102|127|850 |865|898,TC:nil,Content:3|15|50,EDM:-3,IP:-2,URL:0,File:nil,RT:nil,Bulk:ni l,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE :0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: 6db7080883ea11f1aa26b74ffac11d73-20260720 X-User: yijiangshan@kylinos.cn Received: from localhost.localdomain [(116.128.244.171)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 958085240; Mon, 20 Jul 2026 11:23:51 +0800 From: Jiangshan Yi To: dhowells@redhat.com, lukas@wunner.de, ignat@linux.win, herbert@gondor.apana.org.au, davem@davemloft.net Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, keyrings@vger.kernel.org, 13667453960@163.com, Jiangshan Yi Subject: [PATCH] crypto: pkcs7 - Use constant-time message digest comparison Date: Mon, 20 Jul 2026 11:23:16 +0800 Message-Id: <20260720032316.210113-1-yijiangshan@kylinos.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The message digest comparison in pkcs7_verify() uses memcmp(), whose execution time depends on the position of the first mismatched byte. This creates a timing side-channel that could allow an attacker to forge PKCS#7 signatures byte by byte. Replace memcmp() with crypto_memneq() to perform a constant-time comparison, consistent with the rest of the crypto subsystem (gcm, ccm, chacha20poly1305, rsassa-pkcs1, krb5, verify_pefile, etc.). Add an explicit include since this file did not previously pull in the crypto_memneq() declaration. Signed-off-by: Jiangshan Yi --- crypto/asymmetric_keys/pkcs7_verify.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys= /pkcs7_verify.c index 474e2c1ae21b..8c619b252ca5 100644 --- a/crypto/asymmetric_keys/pkcs7_verify.c +++ b/crypto/asymmetric_keys/pkcs7_verify.c @@ -14,6 +14,7 @@ #include #include #include +#include #include "pkcs7_parser.h" =20 /* @@ -93,8 +94,8 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, goto error; } =20 - if (memcmp(sig->m, sinfo->msgdigest, - sinfo->msgdigest_len) !=3D 0) { + if (crypto_memneq(sig->m, sinfo->msgdigest, + sinfo->msgdigest_len)) { pr_warn("Sig %u: Message digest doesn't match\n", sinfo->index); ret =3D -EKEYREJECTED; --=20 2.25.1