From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BC07F4949F7 for ; Wed, 29 Jul 2026 13:55:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785333322; cv=none; b=iUedUv9VURBl1nOJwAY3zGWQtccDOJ5A2eKiT4+2FV1pwx8tBX/Qv91F/ZnLKiugsEXb7+q2eKy476qZAeR8Np4jEFeGXUXBywyWLVUBFG5ZrxOeyqgkIwXDs42s6vIdhWKJdznyK9xrxGZZ3cl81X+wGiusuU1hDOAyF0iXOfk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785333322; c=relaxed/simple; bh=bNNTKeRpxaNegufHnK7tqA+HzH1ez6DI2LwZ3r6HKck=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=ErrJPQew8J5F3C82VXhh/e5UepQQyrLR5ZEBI/8bLEnYyJYR+CdMTpdsWeZG/CLuxS6rAaa9YLioV/tVQJGX/pWosZI2NfBNpvKt82zsuJ3rOyJI3Vx9LhzLcgXM9TIWgnoAfeLFIKM1ReQOBAYikEj12tWTzDghoT7axo3aLYM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uRIwgrCZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="uRIwgrCZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8C571F00A3A; Wed, 29 Jul 2026 13:55:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785333317; bh=6D5BDUMCjKtFRyibZjSB/d0168M8zh9+oAKIec+yO3A=; h=Subject:To:Cc:From:Date; b=uRIwgrCZs06ORc8FQdoagGJ7XR34q9Vud/uoTzXjsGj6InsgK0GGk/TQHmb6VGJDT BFOy4U4VsapNpIceuHebS1TSc17nFkkHar8a/7h8Pvg//mBkLuAsb2cq0M9V8o1YyO zbEtV/+7YhZn6WrDHpXSZpshJHcCny6nuOnYjaxc= Subject: FAILED: patch "[PATCH] ksmbd: defer destroy_previous_session() until after NTLM" failed to apply to 5.15-stable tree To: james_montgomery@disroot.org,linkinjeon@kernel.org,stfrench@microsoft.com Cc: From: Date: Wed, 29 Jul 2026 15:55:04 +0200 Message-ID: <2026072903-union-lagging-6c3f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x c74801ee524f477c174a1899782b6c3b6918d407 # git commit -s git send-email --to '' --in-reply-to '2026072903-union-lagging-6c3f@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From c74801ee524f477c174a1899782b6c3b6918d407 Mon Sep 17 00:00:00 2001 From: James Montgomery Date: Fri, 3 Jul 2026 15:26:41 -0400 Subject: [PATCH] ksmbd: defer destroy_previous_session() until after NTLM authentication In ntlm_authenticate(), destroy_previous_session() is called using a user pointer resolved from the client-supplied NTLM blob username field before the NTLMv2 response is validated. An authenticated attacker can set the NTLM blob username to match a victim account and set PreviousSessionId to the victim's session ID; destroy_previous_session() destroys the victim's session while ksmbd_decode_ntlmssp_auth_blob() subsequently rejects the request with -EPERM. Move destroy_previous_session() and the prev_id assignment to after ksmbd_decode_ntlmssp_auth_blob() returns success and use sess->user rather than the pre-authentication lookup result. This matches the ordering already used by krb5_authenticate(), where destroy_previous_session() is called only after ksmbd_krb5_authenticate() returns success. Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/linux-cifs/20260702155449.3639773-1-james_montgomery@disroot.org/ Signed-off-by: James Montgomery Acked-by: Namjae Jeon Signed-off-by: Steve French diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index d54b714cc36c..c1ba5e01aa7f 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -1717,11 +1717,6 @@ static int ntlm_authenticate(struct ksmbd_work *work, return -EPERM; } - /* Check for previous session */ - prev_id = le64_to_cpu(req->PreviousSessionId); - if (prev_id && prev_id != sess->id) - destroy_previous_session(conn, user, prev_id); - if (sess->state == SMB2_SESSION_VALID) { /* * Reuse session if anonymous try to connect @@ -1761,6 +1756,10 @@ static int ntlm_authenticate(struct ksmbd_work *work, } } + prev_id = le64_to_cpu(req->PreviousSessionId); + if (prev_id && prev_id != sess->id) + destroy_previous_session(conn, sess->user, prev_id); + /* * If session state is SMB2_SESSION_VALID, We can assume * that it is reauthentication. And the user/password