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 EFE64283FFB; Thu, 25 Jun 2026 13:08:45 +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=1782392928; cv=none; b=sfFk7PnE777rin/WWh3O6QGH7ymyttc98vdBakArZU8eSSqf7KwYTLlgDBU9aPWERrl79qeNAMyS5JSGI+jBkdmmUJjXdTt0/QGXOjQWACjDC00wWwa99oLC7JRHEXiYGyon2a7zTyLfgXJPiy/Dt01HU/q2xDIY+EloIhm9dHo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782392928; c=relaxed/simple; bh=JrsK34o0h7mYR2QVIIsn8KiaWxyGHNSgtqibW+0oiGo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pdzYdBffvu2ET4IFQ9h9alNUTZWECsPpDShFTR+OnCbyxf1C2hwTijh6ej+IDQHXq7SOFUttSpDpTuFSHpm8bxKxn00y5EupuzaKeKDeut+qaR1k5KdZrmV6gbQW8h74EevqxoNnaNs/XHqTwvLfcUs3yTOaRDmClPBYbx++1lk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Wt/Bvlpk; 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="Wt/Bvlpk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FD5D1F00A3A; Thu, 25 Jun 2026 13:08:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1782392925; bh=mfT+QHpdfF2XjHCMYpBQEiNbGej6hLrJFqBuKi4YJn0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Wt/BvlpkrMKJmba8OaiZgYkySLAapPUtxbKYGHnVfD9WTGwZ2VFF+K9Ir3Nm9r0Zy 0Fxjmb4PHMMQI/9X9qSL66/lAu2e2j3+EXwPxjIXCE6Z7AK9vwJEz6nLu3W3a5pl3X tsgSx7G8skc+sex8MulvcA4hl25pUF0PZMB/ubsg= 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 6.18 57/60] ksmbd: reject non-VALID session in compound request branch Date: Thu, 25 Jun 2026 14:03:42 +0100 Message-ID: <20260625125654.080287812@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260625125645.554579168@linuxfoundation.org> References: <20260625125645.554579168@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 6.18-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; }