From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 644901547C0; Tue, 10 Mar 2026 19:50:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773172258; cv=none; b=fOuAT6vE4mceKp0dIq4RGlAAd0HgnhXcyxVR2HWQGnCjF9+orNq78voS0/u7ObCqaUTRe7n8nCau28bkCQaR4/CfdMFsAtyH97RJvD0sx8tv0P7yVJYLPRsNzqEIP+HMVGlLnYN9XzjyAq+oqPXDzjibICLw3cHkq+BW6ntnhZo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773172258; c=relaxed/simple; bh=uEmV2RTrQnCjH4X7Ie4Sws6B5LZKfiBkJYJ0NImPwbE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=rpR9JpoTvq/9ZTvwzUQ891FgDsn/jrH5kZCu4AyV2K/k8PfEogLK8vAzQUYOGqKFmJcWBfkLiuQLWhOezlQR/j91Bkzk3lPrI1XybPjifDyiQ3fd6LE7931Co2LH7JA7qlWqd3vDmi3QgPUh0GxrNFL8mWKlQ/z+84Zxmcf0GcI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ceDA+lUE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ceDA+lUE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61307C19423; Tue, 10 Mar 2026 19:50:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773172258; bh=uEmV2RTrQnCjH4X7Ie4Sws6B5LZKfiBkJYJ0NImPwbE=; h=From:To:Cc:Subject:Date:From; b=ceDA+lUEMAb483pU2XEiFizFoadOdgkyf5WL742+ZqDiqD/eja2oNZy5Dt9V4uYrE 0ric0ihtFp8XHD4clN3s/rDO0Npes8O9NlXf7U4p1aY7rd2aREeSC58il2W3VCaMLe ZypPCgR02isNHD2KKtPkJ7IBVVCMp/+1GPI+a+LHtaVVUXMjaokc6VgVhlBpiTAPwT acXaAetFrymMvxAeiwHRb0il0tlNMmK4yVnkXd3GjKUlqu5B5w+WzO3MOyqDufH2k8 hzdtsT1LCzBfyc9pZS1ngRKZ2HpJ+24/SsFgXZem4u+2BsmdSINBKyOpw4PxJmSE61 iJhF3M3cshRSQ== From: Eric Biggers To: stable@vger.kernel.org Cc: linux-crypto@vger.kernel.org, linux-cifs@vger.kernel.org, Eric Biggers , "Paulo Alcantara (Red Hat)" , Steve French Subject: [PATCH 6.12] smb: client: Compare MACs in constant time Date: Tue, 10 Mar 2026 12:50:49 -0700 Message-ID: <20260310195049.70659-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit commit 26bc83b88bbbf054f0980a4a42047a8d1e210e4c upstream. To prevent timing attacks, MAC comparisons need to be constant-time. Replace the memcmp() with the correct function, crypto_memneq(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Acked-by: Paulo Alcantara (Red Hat) Signed-off-by: Eric Biggers Signed-off-by: Steve French --- fs/smb/client/cifsencrypt.c | 3 ++- fs/smb/client/smb2transport.c | 4 +++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/smb/client/cifsencrypt.c b/fs/smb/client/cifsencrypt.c index 7c61c1e944c7a..179aaf7674c7f 100644 --- a/fs/smb/client/cifsencrypt.c +++ b/fs/smb/client/cifsencrypt.c @@ -22,10 +22,11 @@ #include #include #include #include "../common/arc4.h" #include +#include static size_t cifs_shash_step(void *iter_base, size_t progress, size_t len, void *priv, void *priv2) { struct shash_desc *shash = priv; @@ -255,11 +256,11 @@ int cifs_verify_signature(struct smb_rqst *rqst, return rc; /* cifs_dump_mem("what we think it should be: ", what_we_think_sig_should_be, 16); */ - if (memcmp(server_response_sig, what_we_think_sig_should_be, 8)) + if (crypto_memneq(server_response_sig, what_we_think_sig_should_be, 8)) return -EACCES; else return 0; } diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c index 475b36c27f654..87f189894b1e1 100644 --- a/fs/smb/client/smb2transport.c +++ b/fs/smb/client/smb2transport.c @@ -17,10 +17,11 @@ #include #include #include #include #include +#include #include "cifsglob.h" #include "cifsproto.h" #include "smb2proto.h" #include "cifs_debug.h" #include "../common/smb2status.h" @@ -730,11 +731,12 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server) rc = server->ops->calc_signature(rqst, server, true); if (rc) return rc; - if (memcmp(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE)) { + if (crypto_memneq(server_response_sig, shdr->Signature, + SMB2_SIGNATURE_SIZE)) { cifs_dbg(VFS, "sign fail cmd 0x%x message id 0x%llx\n", shdr->Command, shdr->MessageId); return -EACCES; } else return 0; base-commit: 39b686f8d57d7506af7789e915fe7fd103b0fe57 -- 2.53.0