[PATCH 5.19 009/207] smb3: fix temporary data corruption in collapse range

Greg Kroah-Hartman
2022-09-26T11:34:58Z

From: Steve French <stfrench@microsoft.com>

[ Upstream commit fa30a81f255a56cccd89552cd6ce7ea6e8d8acc4 ]

collapse range doesn't discard the affected cached region
so can risk temporarily corrupting the file data. This
fixes xfstest generic/031

I also decided to merge a minor cleanup to this into the same patch
(avoiding rereading inode size repeatedly unnecessarily) to make it
clearer.

Cc: stable@vger.kernel.org
Fixes: 5476b5dd82c8b ("cifs: add support for FALLOC_FL_COLLAPSE_RANGE")
Reported-by: David Howells <dhowells@redhat.com>
Tested-by: David Howells <dhowells@redhat.com>
Reviewed-by: David Howells <dhowells@redhat.com>
cc: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/smb2ops.c | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index ef8cb7fbabeb..8e55495c4f7e 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3952,41 +3952,47 @@ static long smb3_collapse_range(struct file *file, struct cifs_tcon *tcon,
{
int rc;
unsigned int xid;
- struct inode *inode;
+ struct inode *inode = file_inode(file);
struct cifsFileInfo *cfile = file->private_data;
- struct cifsInodeInfo *cifsi;
+ struct cifsInodeInfo *cifsi = CIFS_I(inode);
__le64 eof;
+ loff_t old_eof;

xid = get_xid();

- inode = d_inode(cfile->dentry);
- cifsi = CIFS_I(inode);
+ inode_lock(inode);

- if (off >= i_size_read(inode) ||
- off + len >= i_size_read(inode)) {
+ old_eof = i_size_read(inode);
+ if ((off >= old_eof) ||
+ off + len >= old_eof) {
rc = -EINVAL;
goto out;
}

+ filemap_invalidate_lock(inode->i_mapping);
filemap_write_and_wait(inode->i_mapping);
+ truncate_pagecache_range(inode, off, old_eof);

rc = smb2_copychunk_range(xid, cfile, cfile, off + len,
- i_size_read(inode) - off - len, off);
+ old_eof - off - len, off);
if (rc < 0)
- goto out;
+ goto out_2;

- eof = cpu_to_le64(i_size_read(inode) - len);
+ eof = cpu_to_le64(old_eof - len);
rc = SMB2_set_eof(xid, tcon, cfile->fid.persistent_fid,
cfile->fid.volatile_fid, cfile->pid, &eof);
if (rc < 0)
- goto out;
+ goto out_2;

rc = 0;

cifsi->server_eof = i_size_read(inode) - len;
truncate_setsize(inode, cifsi->server_eof);
fscache_resize_cookie(cifs_inode_cookie(inode), cifsi->server_eof);
+out_2:
+ filemap_invalidate_unlock(inode->i_mapping);
out:
+ inode_unlock(inode);
free_xid(xid);
return rc;
}
--
2.35.1