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Commit 71cf8816 authored by Roberto Bergantinos Corpas's avatar Roberto Bergantinos Corpas Committed by Greg Kroah-Hartman
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CIFS: avoid using MID 0xFFFF 



commit 03d9a9fe3f3aec508e485dd3dcfa1e99933b4bdb upstream.

According to MS-CIFS specification MID 0xFFFF should not be used by the
CIFS client, but we actually do. Besides, this has proven to cause races
leading to oops between SendReceive2/cifs_demultiplex_thread. On SMB1,
MID is a 2 byte value easy to reach in CurrentMid which may conflict with
an oplock break notification request coming from server

Signed-off-by: default avatarRoberto Bergantinos Corpas <rbergant@redhat.com>
Reviewed-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: default avatarAurelien Aptel <aaptel@suse.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 42927455

fs/cifs/smb1ops.c

+3 −0
Original line number Diff line number Diff line
@@ -183,6 +183,9 @@ cifs_get_next_mid(struct TCP_Server_Info *server) 
	/* we do not want to loop forever */

	last_mid = cur_mid;

	cur_mid++;

	/* avoid 0xFFFF MID */

	if (cur_mid == 0xffff)

		cur_mid++;



	/*

	 * This nested loop looks more expensive than it is.