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[209.132.180.67]) by mx.google.com with ESMTP id e19si5262849ejd.24.2019.10.27.14.07.38; Sun, 27 Oct 2019 14:08:01 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=Kw9mqOpz; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727926AbfJ0VGN (ORCPT + 99 others); Sun, 27 Oct 2019 17:06:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:52070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727045AbfJ0VGJ (ORCPT ); Sun, 27 Oct 2019 17:06:09 -0400 Received: from localhost (100.50.158.77.rev.sfr.net [77.158.50.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4D0832064A; Sun, 27 Oct 2019 21:06:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572210368; bh=EVUNZKsf8salVAcey8QhyzO1w7hAWnsfMPL7deYWGnk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Kw9mqOpzzOzrrd+yuXkwe0QO4Ev4n0Q8OXFftBfaJmYtR6RgtU+XpAGjacMakFy3+ iyTSxVN2TOF/0q1wP/89WiSpjQCvcdjy75PlqeGMdyyb/9oOAmysA/JJUb4EB99BUf k05WS411u3zWEofoh9JwpsKV4TyhPbfpnbsrtEqo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Roberto Bergantinos Corpas , Ronnie Sahlberg , Aurelien Aptel , Steve French Subject: [PATCH 4.9 42/49] CIFS: avoid using MID 0xFFFF Date: Sun, 27 Oct 2019 22:01:20 +0100 Message-Id: <20191027203200.495671357@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191027203119.468466356@linuxfoundation.org> References: <20191027203119.468466356@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Roberto Bergantinos Corpas commit 03d9a9fe3f3aec508e485dd3dcfa1e99933b4bdb upstream. According to MS-CIFS specification MID 0xFFFF should not be used by the CIFS client, but we actually do. Besides, this has proven to cause races leading to oops between SendReceive2/cifs_demultiplex_thread. On SMB1, MID is a 2 byte value easy to reach in CurrentMid which may conflict with an oplock break notification request coming from server Signed-off-by: Roberto Bergantinos Corpas Reviewed-by: Ronnie Sahlberg Reviewed-by: Aurelien Aptel Signed-off-by: Steve French CC: Stable Signed-off-by: Greg Kroah-Hartman --- fs/cifs/smb1ops.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/cifs/smb1ops.c +++ b/fs/cifs/smb1ops.c @@ -180,6 +180,9 @@ cifs_get_next_mid(struct TCP_Server_Info /* we do not want to loop forever */ last_mid = cur_mid; cur_mid++; + /* avoid 0xFFFF MID */ + if (cur_mid == 0xffff) + cur_mid++; /* * This nested loop looks more expensive than it is.