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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, Pavel Shilovsky <pshilov@microsoft.com>,
        Ronnie Sahlberg <lsahlber@redhat.com>,
        Steve French <stfrench@microsoft.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.20 47/92] CIFS: Do not assume one credit for async responses
Date:   Mon, 18 Feb 2019 14:42:50 +0100
Message-Id: <20190218133459.115314463@linuxfoundation.org>
In-Reply-To: <20190218133454.668268457@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 0fd1d37b0501efc6e295f56ab55cdaff784aa50c ]

If we don't receive a response we can't assume that the server
granted one credit. Assume zero credits in such cases.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/smb2pdu.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index c393ac255af7..28712080add9 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2826,9 +2826,10 @@ smb2_echo_callback(struct mid_q_entry *mid)
 {
 	struct TCP_Server_Info *server = mid->callback_data;
 	struct smb2_echo_rsp *rsp = (struct smb2_echo_rsp *)mid->resp_buf;
-	unsigned int credits_received = 1;
+	unsigned int credits_received = 0;
 
-	if (mid->mid_state == MID_RESPONSE_RECEIVED)
+	if (mid->mid_state == MID_RESPONSE_RECEIVED
+	    || mid->mid_state == MID_RESPONSE_MALFORMED)
 		credits_received = le16_to_cpu(rsp->sync_hdr.CreditRequest);
 
 	DeleteMidQEntry(mid);
@@ -3085,7 +3086,7 @@ smb2_readv_callback(struct mid_q_entry *mid)
 	struct TCP_Server_Info *server = tcon->ses->server;
 	struct smb2_sync_hdr *shdr =
 				(struct smb2_sync_hdr *)rdata->iov[0].iov_base;
-	unsigned int credits_received = 1;
+	unsigned int credits_received = 0;
 	struct smb_rqst rqst = { .rq_iov = rdata->iov,
 				 .rq_nvec = 2,
 				 .rq_pages = rdata->pages,
@@ -3124,6 +3125,9 @@ smb2_readv_callback(struct mid_q_entry *mid)
 		task_io_account_read(rdata->got_bytes);
 		cifs_stats_bytes_read(tcon, rdata->got_bytes);
 		break;
+	case MID_RESPONSE_MALFORMED:
+		credits_received = le16_to_cpu(shdr->CreditRequest);
+		/* fall through */
 	default:
 		if (rdata->result != -ENODATA)
 			rdata->result = -EIO;
@@ -3317,7 +3321,7 @@ smb2_writev_callback(struct mid_q_entry *mid)
 	struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
 	unsigned int written;
 	struct smb2_write_rsp *rsp = (struct smb2_write_rsp *)mid->resp_buf;
-	unsigned int credits_received = 1;
+	unsigned int credits_received = 0;
 
 	switch (mid->mid_state) {
 	case MID_RESPONSE_RECEIVED:
@@ -3345,6 +3349,9 @@ smb2_writev_callback(struct mid_q_entry *mid)
 	case MID_RETRY_NEEDED:
 		wdata->result = -EAGAIN;
 		break;
+	case MID_RESPONSE_MALFORMED:
+		credits_received = le16_to_cpu(rsp->sync_hdr.CreditRequest);
+		/* fall through */
 	default:
 		wdata->result = -EIO;
 		break;
-- 
2.19.1