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 E27183542CF; Tue, 10 Mar 2026 19:51:03 +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=1773172264; cv=none; b=W4Cdz9q0IdlikkmXQ9iWpRa3QfQRpqiBCscmpBDHyDbPgvaDMr01oFgF04iNPdByHdvxGhrzVGWXl+SSdVxrveY7zvBqRhy60DyD3ryMrveysGrT3/jEGs8a+EX4A+vYFN7np8BOqlS68t/alBDxfiRpyFccEY7hPTPSNLVQ5LU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773172264; c=relaxed/simple; bh=Ad47JaXsywSU6JBLYbdP676mE2ZoM/HobzD5EQN8XWc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=pfx76IuO8vjyvpdd1hI+wHkkpvDLK8Ym29dY+T14UEVkW6PC0C1sO0M6/z6VGOJyS//63xKE256AjBdT25t3rKnUwyJezx9OuRjXLOiJ/nWMNA0Ef1JeX1a5O6bO/Qh2FN4296VcOHu2QRCsMWiP1poaB8XonO0+NCTlDt204wQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rhBhcIny; 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="rhBhcIny" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB2EEC19423; Tue, 10 Mar 2026 19:51:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773172263; bh=Ad47JaXsywSU6JBLYbdP676mE2ZoM/HobzD5EQN8XWc=; h=From:To:Cc:Subject:Date:From; b=rhBhcIny72YQS4nwBDnRFNpkRyNRkrynLzNBNd1XZ1w5DvPDFsZwc0RAMonGjfXaI a7RrOEL+HF6GJdLrdnJdyOey8+XZJUTtC7+43VneVLLIyQbXp5vWJFPN30iTW+uf8c 1wkUL6fdTAKysXUe3B8vSXn1bkPYSWb7pUFlSiEsNY3c9gC0J73Dv0HYeocRvQz1eO YquToz2UTm50h3em5n1oOSnB5fcSdgDS6JZPcpX8NGL1czE8NjxUqFTIqKB9vzhsVC rxr65WcDZ+YvtyZpSJJiKyzh8ns0vLcnVoRtyzvq1mMBbMw9qm6/+7xY5YMFoUuWtY YWlrYi/HizebQ== 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 6.6] smb: client: Compare MACs in constant time Date: Tue, 10 Mar 2026 12:50:58 -0700 Message-ID: <20260310195058.70682-1-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 da3d003cb43db..3d6b663212335 100644 --- a/fs/smb/client/cifsencrypt.c +++ b/fs/smb/client/cifsencrypt.c @@ -21,10 +21,11 @@ #include #include #include #include "../common/arc4.h" #include +#include /* * Hash data from a BVEC-type iterator. */ static int cifs_shash_bvec(const struct iov_iter *iter, ssize_t maxsize, @@ -369,11 +370,11 @@ 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 99081e9d6283a..daf8ba2cd8a10 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 "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: 4fc00fe35d46b4fc8dac2eb543a0e3d44bb15f47 -- 2.53.0