[PATCH 5.19 063/192] smb3: missing inode locks in zero range

Greg Kroah-Hartman
2022-09-13T14:15:27Z

From: David Howells <dhowells@redhat.com>

[ Upstream commit c919c164fc87bcca8e80b3b9224492fa5b6455ba ]

smb3 fallocate zero range was not grabbing the inode or filemap_invalidate
locks so could have race with pagemap reinstantiating the page.

Cc: stable@vger.kernel.org
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/smb2ops.c | 55 ++++++++++++++++++++++++++---------------------
1 file changed, 30 insertions(+), 25 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 33357846a01b1..e8a8daa82ed76 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3590,26 +3590,43 @@ get_smb2_acl(struct cifs_sb_info *cifs_sb,
return pntsd;
}

+static long smb3_zero_data(struct file *file, struct cifs_tcon *tcon,
+ loff_t offset, loff_t len, unsigned int xid)
+{
+ struct cifsFileInfo *cfile = file->private_data;
+ struct file_zero_data_information fsctl_buf;
+
+ cifs_dbg(FYI, "Offset %lld len %lld\n", offset, len);
+
+ fsctl_buf.FileOffset = cpu_to_le64(offset);
+ fsctl_buf.BeyondFinalZero = cpu_to_le64(offset + len);
+
+ return SMB2_ioctl(xid, tcon, cfile->fid.persistent_fid,
+ cfile->fid.volatile_fid, FSCTL_SET_ZERO_DATA,
+ (char *)&fsctl_buf,
+ sizeof(struct file_zero_data_information),
+ 0, NULL, NULL);
+}
+
static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon,
loff_t offset, loff_t len, bool keep_size)
{
struct cifs_ses *ses = tcon->ses;
- struct inode *inode;
- struct cifsInodeInfo *cifsi;
+ struct inode *inode = file_inode(file);
+ struct cifsInodeInfo *cifsi = CIFS_I(inode);
struct cifsFileInfo *cfile = file->private_data;
- struct file_zero_data_information fsctl_buf;
long rc;
unsigned int xid;
__le64 eof;

xid = get_xid();

- inode = d_inode(cfile->dentry);
- cifsi = CIFS_I(inode);
-
trace_smb3_zero_enter(xid, cfile->fid.persistent_fid, tcon->tid,
ses->Suid, offset, len);

+ inode_lock(inode);
+ filemap_invalidate_lock(inode->i_mapping);
+
/*
* We zero the range through ioctl, so we need remove the page caches
* first, otherwise the data may be inconsistent with the server.
@@ -3617,26 +3634,12 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon,
truncate_pagecache_range(inode, offset, offset + len - 1);

/* if file not oplocked can't be sure whether asking to extend size */
- if (!CIFS_CACHE_READ(cifsi))
- if (keep_size == false) {
- rc = -EOPNOTSUPP;
- trace_smb3_zero_err(xid, cfile->fid.persistent_fid,
- tcon->tid, ses->Suid, offset, len, rc);
- free_xid(xid);
- return rc;
- }
-
- cifs_dbg(FYI, "Offset %lld len %lld\n", offset, len);
-
- fsctl_buf.FileOffset = cpu_to_le64(offset);
- fsctl_buf.BeyondFinalZero = cpu_to_le64(offset + len);
+ rc = -EOPNOTSUPP;
+ if (keep_size == false && !CIFS_CACHE_READ(cifsi))
+ goto zero_range_exit;

- rc = SMB2_ioctl(xid, tcon, cfile->fid.persistent_fid,
- cfile->fid.volatile_fid, FSCTL_SET_ZERO_DATA,
- (char *)&fsctl_buf,
- sizeof(struct file_zero_data_information),
- 0, NULL, NULL);
- if (rc)
+ rc = smb3_zero_data(file, tcon, offset, len, xid);
+ if (rc < 0)
goto zero_range_exit;

/*
@@ -3649,6 +3652,8 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon,
}

zero_range_exit:
+ filemap_invalidate_unlock(inode->i_mapping);
+ inode_unlock(inode);
free_xid(xid);
if (rc)
trace_smb3_zero_err(xid, cfile->fid.persistent_fid, tcon->tid,
--
2.35.1