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 8B03A2877F7; Thu, 25 Jun 2026 13:12:47 +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=1782393168; cv=none; b=X+7+92jK7O+n2sKDe40gPPsVYw4xyiEybQCk1z40lpA861vxihHFPopycrGWCB1dyXgH2D1bowBbrD0wq6UiQ9vs0a/QNvfVaXEU27vYkKtHWiQ9ccqL27GAy5ZeiYaWoAM1IT7x9bnUfD/SZxyQd2Nzk0mwLIRW1U4OrYWUNfA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782393168; c=relaxed/simple; bh=hcfLVja2mOiWJ/tcHgMD9nZvGX40cCR95wtQkrzmQP4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hHfbJBQtfTiwfm/jcDrOuOMDgDeFKhwuhD7n5tsyFkhPc53ClT/f7VTy7yzPmRy5pX97NsvT/njxllONH4h6TuStOHwl7/WUgZ0QDWgcGvrNTkuz/PxlZuZ0nu8rhlxjm+mNJqCc3h3r9k9P/yW8xMo2t3AAJOJtIOwUFkExUsk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fuuKJdLx; 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="fuuKJdLx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF7551F000E9; Thu, 25 Jun 2026 13:12:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1782393167; bh=W5Nnm+lTDxyvlEqfr4yAZLDvPgqcmN/2pv3WdMYJZhU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fuuKJdLxukqac68dRvYrVTtKkzG6vA1NXxZJHZHIds/jANM2z7uE65pVJb7W62ili gPBsUIml1p5MgSCWjTdwaj/pdkt9Ni+RfPhW6SnNEdnPGxsq2rxnwWrFMafWZhR5Q8 QQXzkBof9nDvfklLraK6R0qNYH/KrGBAuwsVfjXY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gil Portnoy , Namjae Jeon , Steve French Subject: [PATCH 7.1 19/21] ksmbd: reject non-VALID session in compound request branch Date: Thu, 25 Jun 2026 14:04:11 +0100 Message-ID: <20260625125615.927685739@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260625125613.243729608@linuxfoundation.org> References: <20260625125613.243729608@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 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gil Portnoy commit 609ca17d869d04ba249e32cdcbf13c0b1c66f43c upstream. 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: Greg Kroah-Hartman --- fs/smb/server/smb2pdu.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -613,6 +613,11 @@ 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; }