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 A80BF28640B; Thu, 25 Jun 2026 13:11:07 +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=1782393068; cv=none; b=bP091utR+AWnwWQg3pOn6x/XBGWTeKNbucuroADYNb93h1Vtq3At5y38LmN/Wo5xqKyqfzmwe8RDz2t6dfR3NZyJcYHoeVBoVBBe7bL8+mMdWKUwVF4Avp2Gn8QiaAOPXFW4gdqWJWlUSLZJVSrFwJVQK9BA2PdJGB+8wo/41vg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782393068; c=relaxed/simple; bh=QtGwFp2h0vkLigb/OkCnIQyG88/ioZ9xiETxzgh0Y0k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=txvx+b4vWzdpReVqF5ZDXOuxhRaK2TtKuI4+SoxM54Dee0vB8klWJp11yt+fCZgNFTNIxLdMz9QasAML/vSPQLYvolRAA/37sd15kmW4Rwr6XKMIgcB274H0dVpM/6VTw/Na2GqEZYAk71X3g4xPsYSTkvkGP293m2BoD+0VQGI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bbAl/ost; 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="bbAl/ost" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDD601F000E9; Thu, 25 Jun 2026 13:11:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1782393067; bh=BRNx2OFz81uH6v5OVTFLWEkTBDOCArhuVlolvyhYmV8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bbAl/ostiNf35P1pHM54pqs83dxYqhxMQ99bIwgT0Zt/lR+D5Nz0oY2MTH5mMzf2O Aj5N9lZY4Td+2sze89bbELDjWJRHUHj903uWizsxZDbn/ORKR8f/K6kGFixUzLhYfx muXSw19n2eomFyOsF7rRFWGT4cmljz/7OERdGJgg= 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 7.0 47/49] ksmbd: reject non-VALID session in compound request branch Date: Thu, 25 Jun 2026 14:03:59 +0100 Message-ID: <20260625125644.124988326@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260625125637.527552689@linuxfoundation.org> References: <20260625125637.527552689@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 7.0-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 @@ -614,6 +614,11 @@ 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; }