linux-kernel - [PATCH AUTOSEL 4.9 09/10] cifs: revalidate mapping when we open files for SMB1 POSIX

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Message-Id: <20210329222401.2383930-9-sashal@kernel.org>
Date:   Mon, 29 Mar 2021 18:24:00 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Ronnie Sahlberg <lsahlber@...hat.com>, Paulo Alcantara <pc@....nz>,
        Steve French <stfrench@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org
Subject: [PATCH AUTOSEL 4.9 09/10] cifs: revalidate mapping when we open files for SMB1 POSIX

From: Ronnie Sahlberg <lsahlber@...hat.com>

[ Upstream commit cee8f4f6fcabfdf229542926128e9874d19016d5 ]

RHBZ: 1933527

Under SMB1 + POSIX, if an inode is reused on a server after we have read and
cached a part of a file, when we then open the new file with the
re-cycled inode there is a chance that we may serve the old data out of cache
to the application.
This only happens for SMB1 (deprecated) and when posix are used.
The simplest solution to avoid this race is to force a revalidate
on smb1-posix open.

Signed-off-by: Ronnie Sahlberg <lsahlber@...hat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@....nz>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/file.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 24508b69e78b..e2ce90fc504e 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -163,6 +163,7 @@ int cifs_posix_open(char *full_path, struct inode **pinode,
 			goto posix_open_ret;
 		}
 	} else {
+		cifs_revalidate_mapping(*pinode);
 		cifs_fattr_to_inode(*pinode, &fattr);
 	}
 
-- 
2.30.1