linux-kernel - [PATCH 5.15 523/667] f2fs: fix fallocate to use file_modified to update permissions consistently

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue,  7 Jun 2022 19:03:08 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, stable@...nel.org,
        Chao Yu <chao.yu@...o.com>, Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 5.15 523/667] f2fs: fix fallocate to use file_modified to update permissions consistently

From: Chao Yu <chao@...nel.org>

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@...nel.org
Signed-off-by: Chao Yu <chao.yu@...o.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/f2fs/file.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1768,6 +1768,10 @@ static long f2fs_fallocate(struct file *

 	inode_lock(inode);

+	ret = file_modified(file);
+	if (ret)
+		goto out;
+
 	if (mode & FALLOC_FL_PUNCH_HOLE) {
 		if (offset >= inode->i_size)
 			goto out;