[PATCH 4.20 46/92] CIFS: Fix credit calculations in compound mid callback

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

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

[ Upstream commit 3d3003fce8e837acc4e3960fe3cbabebc356dcb5 ]

The current code doesn't do proper accounting for credits
in SMB1 case: it adds one credit per response only if we get
a complete response while it needs to return it unconditionally.
Fix this and also include malformed responses for SMB2+ into
accounting for credits because such responses have Credit
Granted field, thus nothing prevents to get a proper credit
value from them.

Signed-off-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Reviewed-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/cifs/smb2ops.c   |  6 +++++-
 fs/cifs/transport.c | 11 +----------
 2 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index d7dd7d38fad6..aa71e620f3cd 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -154,7 +154,11 @@ smb2_get_credits(struct mid_q_entry *mid)
 {
 	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)mid->resp_buf;
 
-	return le16_to_cpu(shdr->CreditRequest);
+	if (mid->mid_state == MID_RESPONSE_RECEIVED
+	    || mid->mid_state == MID_RESPONSE_MALFORMED)
+		return le16_to_cpu(shdr->CreditRequest);
+
+	return 0;
 }
 
 static int
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 0dab276eced8..6f937e826910 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -784,17 +784,8 @@ static void
 cifs_compound_callback(struct mid_q_entry *mid)
 {
 	struct TCP_Server_Info *server = mid->server;
-	unsigned int optype = mid->optype;
-	unsigned int credits_received = 0;
 
-	if (mid->mid_state == MID_RESPONSE_RECEIVED) {
-		if (mid->resp_buf)
-			credits_received = server->ops->get_credits(mid);
-		else
-			cifs_dbg(FYI, "Bad state for cancelled MID\n");
-	}
-
-	add_credits(server, credits_received, optype);
+	add_credits(server, server->ops->get_credits(mid), mid->optype);
 }
 
 static void
-- 
2.19.1