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 A989C35A38A; Tue, 10 Mar 2026 19:51:07 +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=1773172267; cv=none; b=tm7qxLAce8jYT3nPprQVRels9hx+kSU2dZisbm7/EBMAjelA0YhIuWVIrmUvsuE03cKPFj9HFnHQDTTO71h+ldDVExZevwc9Nm0AZLDBR+DrsaUfxqprtD75wClUcWU84qtwK90oZlQpwQAb9Be+4xwgJbSDza7ZaTWJ5jklLSk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773172267; c=relaxed/simple; bh=PHVqUmdZOJoCMt1Z2VcfyTE7sGV0SetRg8yMWp20OkI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=kl2yJ86VU43C5WAiTPUUNjFQWZc/sn0a3zW4Oz/wSqJnPY/A8V6fTUGzzFGgsnWrgvYm4H5oJpkgEkt9ujaZeU1ZUX/HyAG0cyZKa8M0lbxUhLP/Rp15UCwOnh8GiLVg4vq51Ayaa9kA1fGFOJHNPgNCF/7knD3KcGR6w5ftH/s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lvKQoaJw; 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="lvKQoaJw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD3F6C19423; Tue, 10 Mar 2026 19:51:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773172267; bh=PHVqUmdZOJoCMt1Z2VcfyTE7sGV0SetRg8yMWp20OkI=; h=From:To:Cc:Subject:Date:From; b=lvKQoaJwEl9VFCiAKvp5nfgXxOlSV+4li4sni0hylLks/6hWQT+dzpQ4YcaFrbcrA N/swEd0egd964vxTXBetj3krrhVOKGwzbiYoQhLIXEDEm9cPtvK+MuTCQKLqkbom7O 35DOP5FkmM/tG/9iui7B51nUjrtF0qAGDTqhPSgPA2KPECY0vAa0lxfjmAmZNkwS03 Jlavg8j0Xq9Zp5UZHTMEmBEIPT6kB1p+EB39zocwteLv0mjZ0AW/XVBGJ7YgKPPC7c 4K5MQVwexNK9y5qWv38tB9kTYIHSdb74nRqPsMBfHO5U937CeXEcRqX2n3E7rtMyfE uazen/Gd1YriA== 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 6.1] smb: client: Compare MACs in constant time Date: Tue, 10 Mar 2026 12:51:03 -0700 Message-ID: <20260310195103.70705-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-cifs@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 d3d4cf6321fd5..743098804edcc 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 int __cifs_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server, char *signature, struct shash_desc *shash) { @@ -241,11 +242,11 @@ 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 763cf946e8491..73d281abd265a 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" @@ -697,11 +698,12 @@ 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: f2ddafa93a259310ca47507153b7811ec54ab7fd -- 2.53.0