From: Amir Goldstein <amir73il@gmail.com>
Date: Mon, 17 Oct 2022 15:06:39 +0000 (+0200)
Subject: ovl: remove privs in ovl_fallocate()
X-Git-Tag: v5.15.92~1400
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=26bffaf6784a1c8deb25776be8924a7c3407b7bd;p=platform%2Fkernel%2Flinux-rpi.git

ovl: remove privs in ovl_fallocate()

[ Upstream commit 23a8ce16419a3066829ad4a8b7032a75817af65b ]

Underlying fs doesn't remove privs because fallocate is called with
privileged mounter credentials.

This fixes some failure in fstests generic/683..687.

Fixes: aab8848cee5e ("ovl: add ovl_fallocate()")
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index b56e1f7..28cb05e 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -516,9 +516,16 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
 	const struct cred *old_cred;
 	int ret;
 
+	inode_lock(inode);
+	/* Update mode */
+	ovl_copyattr(inode);
+	ret = file_remove_privs(file);
+	if (ret)
+		goto out_unlock;
+
 	ret = ovl_real_fdget(file, &real);
 	if (ret)
-		return ret;
+		goto out_unlock;
 
 	old_cred = ovl_override_creds(file_inode(file)->i_sb);
 	ret = vfs_fallocate(real.file, mode, offset, len);
@@ -529,6 +536,9 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
 
 	fdput(real);
 
+out_unlock:
+	inode_unlock(inode);
+
 	return ret;
 }