[PATCH 4/5] overlayfs: Check for range bounds before calling i_op->fiemap()

From: Ritesh Harjani <riteshh@linux.ibm.com>
To: linux-ext4@vger.kernel.org
Cc: jack@suse.cz, tytso@mit.edu, adilger@dilger.ca,
	darrick.wong@oracle.com, hch@infradead.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Ritesh Harjani <riteshh@linux.ibm.com>,
	Murphy Zhou <jencce.kernel@gmail.com>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Amir Goldstein <amir73il@gmail.com>,
	linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org
Subject: [PATCH 4/5] overlayfs: Check for range bounds before calling i_op->fiemap()
Date: Thu, 23 Apr 2020 16:17:56 +0530	[thread overview]
Message-ID: <39b4bf94f6723831a9798237bb1b4ae14da04d98.1587555962.git.riteshh@linux.ibm.com> (raw)
In-Reply-To: <cover.1587555962.git.riteshh@linux.ibm.com>

Underlying fs may not be able to handle the length in fiemap
beyond sb->s_maxbytes. So similar to how VFS ioctl does it,
add fiemap_check_ranges() check in ovl_fiemap() as well
before calling underlying fs i_op->fiemap() call.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
 fs/overlayfs/inode.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 79e8994e3bc1..9bcd2e96faad 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -455,16 +455,21 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	int err;
 	struct inode *realinode = ovl_inode_real(inode);
 	const struct cred *old_cred;
+	u64 length;
 
 	if (!realinode->i_op->fiemap)
 		return -EOPNOTSUPP;
 
+	err = fiemap_check_ranges(realinode->i_sb, start, len, &length);
+	if (err)
+		return err;
+
 	old_cred = ovl_override_creds(inode->i_sb);
 
 	if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
 		filemap_write_and_wait(realinode->i_mapping);
 
-	err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
+	err = realinode->i_op->fiemap(realinode, fieinfo, start, length);
 	revert_creds(old_cred);
 
 	return err;
-- 
2.21.0

