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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Namjae Jeon <linkinjeon@kernel.org>,
        Steve French <stfrench@microsoft.com>
Subject: [PATCH 5.15 037/846] ksmbd: move credit charge deduction under processing request
Date:   Mon, 24 Jan 2022 19:32:34 +0100
Message-Id: <20220124184102.220566073@linuxfoundation.org>
In-Reply-To: <20220124184100.867127425@linuxfoundation.org>
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From: Namjae Jeon <linkinjeon@kernel.org>

commit 914d7e5709ac59ded70bea7956d408fe2acd7c3c upstream.

Moves the credit charge deduction from total_credits under the processing
a request. When repeating smb2 lock request and other command request,
there will be a problem that ->total_credits does not decrease.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/ksmbd/smb2misc.c |    7 ++-----
 fs/ksmbd/smb2pdu.c  |   16 ++++++++++------
 2 files changed, 12 insertions(+), 11 deletions(-)

--- a/fs/ksmbd/smb2misc.c
+++ b/fs/ksmbd/smb2misc.c
@@ -290,7 +290,7 @@ static int smb2_validate_credit_charge(s
 	unsigned int req_len = 0, expect_resp_len = 0, calc_credit_num, max_len;
 	unsigned short credit_charge = le16_to_cpu(hdr->CreditCharge);
 	void *__hdr = hdr;
-	int ret;
+	int ret = 0;
 
 	switch (hdr->Command) {
 	case SMB2_QUERY_INFO:
@@ -333,10 +333,7 @@ static int smb2_validate_credit_charge(s
 	}
 
 	spin_lock(&conn->credits_lock);
-	if (credit_charge <= conn->total_credits) {
-		conn->total_credits -= credit_charge;
-		ret = 0;
-	} else {
+	if (credit_charge > conn->total_credits) {
 		ksmbd_debug(SMB, "Insufficient credits granted, given: %u, granted: %u\n",
 			    credit_charge, conn->total_credits);
 		ret = 1;
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -301,9 +301,8 @@ int smb2_set_rsp_credits(struct ksmbd_wo
 	struct smb2_hdr *req_hdr = ksmbd_req_buf_next(work);
 	struct smb2_hdr *hdr = ksmbd_resp_buf_next(work);
 	struct ksmbd_conn *conn = work->conn;
-	unsigned short credits_requested;
+	unsigned short credits_requested, aux_max;
 	unsigned short credit_charge, credits_granted = 0;
-	unsigned short aux_max, aux_credits;
 
 	if (work->send_no_response)
 		return 0;
@@ -318,6 +317,13 @@ int smb2_set_rsp_credits(struct ksmbd_wo
 
 	credit_charge = max_t(unsigned short,
 			      le16_to_cpu(req_hdr->CreditCharge), 1);
+	if (credit_charge > conn->total_credits) {
+		ksmbd_debug(SMB, "Insufficient credits granted, given: %u, granted: %u\n",
+			    credit_charge, conn->total_credits);
+		return -EINVAL;
+	}
+
+	conn->total_credits -= credit_charge;
 	credits_requested = max_t(unsigned short,
 				  le16_to_cpu(req_hdr->CreditRequest), 1);
 
@@ -327,13 +333,11 @@ int smb2_set_rsp_credits(struct ksmbd_wo
 	 * TODO: Need to adjuct CreditRequest value according to
 	 * current cpu load
 	 */
-	aux_credits = credits_requested - 1;
 	if (hdr->Command == SMB2_NEGOTIATE)
-		aux_max = 0;
+		aux_max = 1;
 	else
 		aux_max = conn->vals->max_credits - credit_charge;
-	aux_credits = min_t(unsigned short, aux_credits, aux_max);
-	credits_granted = credit_charge + aux_credits;
+	credits_granted = min_t(unsigned short, credits_requested, aux_max);
 
 	if (conn->vals->max_credits - conn->total_credits < credits_granted)
 		credits_granted = conn->vals->max_credits -