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 9A39C43B4AB; Tue, 21 Jul 2026 22:27:42 +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=1784672863; cv=none; b=T8tQDUbfMZFw5bB6TJAHTeR2HwWIUsU/eclb0+pSyn2swZRJECJJtAIcaS5Xu+ShdTGoY5FdAGs798cckDBnysFkZ7WLEuaSiEIw6JohCwH/Wg+g09Ouhbh6EucmspafqY0T8pog6jYNxfWK2TmlofbXmZ7jw+XD12AMC+qs3e8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784672863; c=relaxed/simple; bh=dyK+VBmkJw7LSukkFaW1Nxm0vyUx/k5uxmngXp/Y1AM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=a5fQ5oM/PzVPCQWDoIYou+aTkycibLeShUb6UdDLAJ0MAtcDLcCrXPy5/9/NEpUnoEQNbH3XfpyFwPXYALzSSvwzA4LZIGP1FzArW9iNvCtCYMgzDUhECnxgZQ9Uf2eBZGJemYgfVOKntVtzwWDSUXHYIiiaZUT3MBtcsHtmuUA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BPCUL4s1; 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="BPCUL4s1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFA8E1F00A3A; Tue, 21 Jul 2026 22:27:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784672862; bh=Of6Db9Ku1hSVriEYp4NiwvX1+Th8UIoKoyvuaZBW0cY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BPCUL4s1V4j4CcwIdLq4P1KSam4Op9PNjwUj+8fWyHkKS9lJNIJx2mnxx03IZZHTS il4VB0wcaqebfNuo0yT36rb8MCwjbWwtUkdASzJ9Xhry6NinQdDLbjwuBqhPrzpUsl f+9Mkt0ZrqlrR1r2Me8x/nE3vmROGZ/qKHU31XMI= 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 , Sasha Levin Subject: [PATCH 5.15 786/843] ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc Date: Tue, 21 Jul 2026 17:27:01 +0200 Message-ID: <20260721152423.744843981@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Kroah-Hartman [ Upstream commit ad0057fb91218914d6c98268718ceb9d59b388e1 ] 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 Stable-dep-of: c1016dd1d8b2 ("ksmbd: track the connection owning a byte-range lock") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/ksmbd/connection.c | 1 + fs/ksmbd/smb2pdu.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) --- a/fs/ksmbd/connection.c +++ b/fs/ksmbd/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); kfree(conn); } --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -1920,7 +1920,7 @@ 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; }