From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AE1F233F5A9; Mon, 20 Apr 2026 16:10:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776701429; cv=none; b=lagEQ/MfSW3usHZWms1xARoMu4IRig3xrduFtxzyqXFfUkSKBeIVyAHzVzo9PDNFb+Dz3P/Sad7yYccZt4SBJArzDTs56PqQO8efls8c7A7KQN02vzwwfOn6L0zcr9MJ/W7ZyFUpgP5jAqA1Qdw7Z/i6NoPaO3Tpa84sBZ8LI0w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776701429; c=relaxed/simple; bh=B0xknbStO549k1VP3VlMj9q0eHnq2JDjcyk74mNx9Co=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RlIJ6SO6hhxMGGYroL4/CWz6PHkiOT5klTzozrHVdptcKeU/KRQS8+KmfSRMUWDZBZCVzJZwqpcXy2PGRQjVXIjdngdsPm+Zv7I0Q2++iKayuQGKQIgzxh13kQoK54gfAcAi6PsjVFTrEs+t0sGBCzSh1FwYW6JWQk2rhRWQYB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=p7YKR8Kk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="p7YKR8Kk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44F34C19425; Mon, 20 Apr 2026 16:10:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776701429; bh=B0xknbStO549k1VP3VlMj9q0eHnq2JDjcyk74mNx9Co=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p7YKR8KkDg3Sjp2Ps039U9nDliTnz7u7FY2p3bLh1fjC4z0iYY9ohM4RBhvo6cYeH SPHddzeZYs0kYn0m67Aph7UJxMX6JGmNQw4KbRi80L+n7cuwKFO445u7NE4eJkb7VP ir7aDh2gdo1SCTEupYzXSuIT1Hjfu8Z/xOffxYt8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Namjae Jeon , Steve French , Sergey Senozhatsky , Tom Talpey , linux-cifs@vger.kernel.org, stable@kernel.org, Steve French Subject: [PATCH 6.12 110/162] ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc Date: Mon, 20 Apr 2026 17:42:22 +0200 Message-ID: <20260420153931.025296062@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420153927.006696811@linuxfoundation.org> References: <20260420153927.006696811@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Kroah-Hartman commit ad0057fb91218914d6c98268718ceb9d59b388e1 upstream. The kernel ASN.1 BER decoder calls action callbacks incrementally as it walks the input. When ksmbd_decode_negTokenInit() reaches the mechToken [2] OCTET STRING element, ksmbd_neg_token_alloc() allocates conn->mechToken immediately via kmemdup_nul(). If a later element in the same blob is malformed, then the decoder will return nonzero after the allocation is already live. This could happen if mechListMIC [3] overrunse the enclosing SEQUENCE. decode_negotiation_token() then sets conn->use_spnego = false because both the negTokenInit and negTokenTarg grammars failed. The cleanup at the bottom of smb2_sess_setup() is gated on use_spnego: if (conn->use_spnego && conn->mechToken) { kfree(conn->mechToken); conn->mechToken = NULL; } so the kfree is skipped, causing the mechToken to never be freed. This codepath is reachable pre-authentication, so untrusted clients can cause slow memory leaks on a server without even being properly authenticated. Fix this up by not checking check for use_spnego, as it's not required, so the memory will always be properly freed. At the same time, always free the memory in ksmbd_conn_free() incase some other failure path forgot to free it. Cc: Namjae Jeon Cc: Steve French Cc: Sergey Senozhatsky Cc: Tom Talpey Cc: linux-cifs@vger.kernel.org Cc: Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/connection.c | 1 + fs/smb/server/smb2pdu.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) --- a/fs/smb/server/connection.c +++ b/fs/smb/server/connection.c @@ -39,6 +39,7 @@ void ksmbd_conn_free(struct ksmbd_conn * xa_destroy(&conn->sessions); kvfree(conn->request_buf); kfree(conn->preauth_info); + kfree(conn->mechToken); if (atomic_dec_and_test(&conn->refcnt)) { conn->transport->ops->free_transport(conn->transport); kfree(conn); --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -1921,7 +1921,7 @@ out_err: else if (rc) rsp->hdr.Status = STATUS_LOGON_FAILURE; - if (conn->use_spnego && conn->mechToken) { + if (conn->mechToken) { kfree(conn->mechToken); conn->mechToken = NULL; }