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f2fs: fix fallocate to use file_modified to update permissions consistently

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commit 958ed92922028ec67f504dcdc72bfdfd0f43936a upstream.

This patch tries to fix permission consistency issue as all other
mainline filesystems.

Since the initial introduction of (posix) fallocate back at the turn of
the century, it has been possible to use this syscall to change the
user-visible contents of files.  This can happen by extending the file
size during a preallocation, or through any of the newer modes (punch,
zero, collapse, insert range).  Because the call can be used to change
file contents, we should treat it like we do any other modification to a
file -- update the mtime, and drop set[ug]id privileges/capabilities.

The VFS function file_modified() does all this for us if pass it a
locked inode, so let's make fallocate drop permissions correctly.

Cc: stable@kernel.org
Signed-off-by: Chao Yu <chao.yu@oppo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chao Yu 2022-05-17 11:37:23 +08:00 committed by Greg Kroah-Hartman
parent ef221b738b
commit 2221a2d410
1 changed files with 4 additions and 0 deletions
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4
fs/f2fs/file.c
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@ -1744,6 +1744,10 @@ static long f2fs_fallocate(struct file *file, int mode,
inode_lock(inode);
ret = file_modified(file);
if (ret)
goto out;
if (mode & FALLOC_FL_PUNCH_HOLE) {
if (offset >= inode->i_size)
goto out;