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 BEC42344D9F; Thu, 2 Jul 2026 16:30:12 +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=1783009815; cv=none; b=M4VtW9bPgDbv4cfX2Xf+gQVbBymNFbdP/Yt6ahEIgKaGc3BFu+lEGxR61Ze7l214WgPYYKAuXAePXVp/KnHkJ6O+iy/XGoJSPxeixai3TJZMX60Qt81x0xpiZOoOiapJr/fa9qzlNjGK0MtD2RYemlwBDcckqmYz/7dGqi6ZFH8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783009815; c=relaxed/simple; bh=OO0v9GxZPN/rj3FvCIIHmiUfHNM4ncdHaRtyqz/7aGo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LpAY5y0Q0+RN6n88FyU4tA92U3FbIHuNBpwJrwpKuMnxW+c/d2rw6DvE1Vcdva+cGflAEhpunSjis3iE9LAdDsNDq6B2X7NuPbPnxXb2EevARXvykk8V/YB/RAhkJajNSJFg6GdFuo+PxrwkBQ9hpZK9j7LXqYwJ/hGCu79rj5E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GVlHcBq3; 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="GVlHcBq3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3E401F00A3A; Thu, 2 Jul 2026 16:30:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783009812; bh=ruWZ15Uua4w09kN/5XZEqIsgW53eewcjxjxQ9HCNrsE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GVlHcBq3Gmi91avgWXTb2DMfZEZDJaXmkOloVWtRwoSpeEbXQgjy/LtyKpmrV+d8b C9FQG4GNtTs5CIFigB2sRsefRg7kwHAHDue5CJH47m0Bs86XE3hHEXLarqR54kxt2S 148nGoCWHEYwqOunEWD+EOL7jrtajB65N9vVLmLk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gil Portnoy , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 5.15 90/95] ksmbd: reject non-VALID session in compound request branch Date: Thu, 2 Jul 2026 18:20:33 +0200 Message-ID: <20260702155111.102668428@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155109.196223802@linuxfoundation.org> References: <20260702155109.196223802@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gil Portnoy [ Upstream commit 609ca17d869d04ba249e32cdcbf13c0b1c66f43c ] smb2_check_user_session() takes a shortcut for any operation that is not the first in a COMPOUND request: it reuses work->sess (the session bound by the first operation) and validates only the SessionId, then returns "valid". It never re-checks work->sess->state == SMB2_SESSION_VALID, and a SessionId of 0xFFFFFFFFFFFFFFFF (ULLONG_MAX, the MS-SMB2 related-operation value) skips even the id comparison. The standalone path (ksmbd_session_lookup_all() plus the SESSION_SETUP state machine) does enforce the VALID state; the compound branch bypasses all of it. A SESSION_SETUP carrying only an NTLM Type-1 (NtLmNegotiate) blob publishes a fresh SMB2_SESSION_IN_PROGRESS session whose sess->user is still NULL (->user is assigned later, by ntlm_authenticate()). Used as operation 1 of a COMPOUND with operation 2 = TREE_CONNECT (related, SessionId=ULLONG_MAX, \\host\IPC$), the tree-connect then runs on that IN_PROGRESS session and reaches ksmbd_ipc_tree_connect_request(), which dereferences user_name(sess->user) with sess->user == NULL (transport_ipc.c:687/701/704) -> remote NULL-pointer dereference and a kernel Oops that wedges the ksmbd worker for all clients. Reject any non-first compound operation that lands on a session which is not SMB2_SESSION_VALID, mirroring the validity the standalone lookup path enforces. SESSION_SETUP itself legitimately runs on an IN_PROGRESS session, but it is never carried as a non-first compound operation, so multi-leg authentication is unaffected by this check. Fixes: 5005bcb42191 ("ksmbd: validate session id and tree id in the compound request") Cc: stable@vger.kernel.org Signed-off-by: Gil Portnoy Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/ksmbd/smb2pdu.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -606,6 +606,11 @@ int smb2_check_user_session(struct ksmbd sess_id, work->sess->id); return -EINVAL; } + if (work->sess->state != SMB2_SESSION_VALID) { + pr_err("compound request on a non-valid session (state %d)\n", + work->sess->state); + return -EINVAL; + } return 1; }