linux-kernel - [PATCH] CIFS: Prevent error log on spurious oplock break

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Date:   Fri, 5 Mar 2021 10:41:07 +0100
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     <pshilov@...rosoft.com>, Steve French <sfrench@...ba.org>
CC:     <kernel@...s.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        <linux-cifs@...r.kernel.org>, <samba-technical@...ts.samba.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] CIFS: Prevent error log on spurious oplock break

The SMB1 version of ->is_oplock_break() returns true even if the FileId
is not found, as long as the oplock break notification message structure
itself appears to be valid.  A true return value makes
cifs_demultiplex_thread() to not print an error message for such
packets.

However, the SMB2 version returns false in such cases, leading to an
error "No task to wake, unknown frame received!" followed by a hexdump
of the packet header being printed by cifs_demultiplex_thread().

Note that before commit fa9c2362497fbd64788063288d ("CIFS: Fix SMB2
oplock break processing"), SMB2 also returned true for the case where a
connection was found but the FileId was not, but it's not clear to me if
that commit really intended to change the behaviour of the error prints.

Change the behaviour of SMB2 to be the same as SMB1 and avoid the error
messages for these packets which we ignore as per the spec.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---
 fs/cifs/smb2misc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index 60d4bd1eae2b..3ea3bda64083 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -679,7 +679,7 @@ smb2_is_valid_lease_break(char *buffer)
 	}
 	spin_unlock(&cifs_tcp_ses_lock);
 	cifs_dbg(FYI, "Can not process lease break - no lease matched\n");
-	return false;
+	return true;
 }

 bool
@@ -755,7 +755,7 @@ smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
 	}
 	spin_unlock(&cifs_tcp_ses_lock);
 	cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
-	return false;
+	return true;
 }

 void
-- 
2.28.0