From b092b3efc7cb239b6f33bb97da0f8812680e1046 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 22 Apr 2021 16:52:32 +0200 Subject: cifs: Fix race between hole punch and page fault Cifs has a following race between hole punching and page fault: CPU1 CPU2 smb3_fallocate() smb3_punch_hole() truncate_pagecache_range() filemap_fault() - loads old data into the page cache SMB2_ioctl(..., FSCTL_SET_ZERO_DATA, ...) And now we have stale data in the page cache. Fix the problem by locking out faults (as well as reads) using mapping->invalidate_lock while hole punch is running. CC: Steve French CC: linux-cifs@vger.kernel.org Signed-off-by: Jan Kara --- fs/cifs/smb2ops.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/cifs') diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index e4c8f603dd58..458c546ce8cd 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -3588,6 +3588,7 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon, return rc; } + filemap_invalidate_lock(inode->i_mapping); /* * We implement the punch hole through ioctl, so we need remove the page * caches first, otherwise the data may be inconsistent with the server. @@ -3605,6 +3606,7 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon, sizeof(struct file_zero_data_information), CIFSMaxBufSize, NULL, NULL); free_xid(xid); + filemap_invalidate_unlock(inode->i_mapping); return rc; } -- cgit v1.2.3