Re: [FOR STABLE] ext4: in ext4_seek_{hole,data}, return -ENXIO for negative offsets

[Theodore Ts'o <tytso@mit.edu>]

On Tue, Oct 10, 2017 at 08:10:49PM +0200, Greg KH wrote:
> No, it fails to apply to 4.9:
> 
> Applying patch ext4-in-ext4_seek_-hole-data-return-enxio-for-negative-offsets.patch
> patching file fs/ext4/file.c
> Hunk #1 succeeded at 590 (offset -5 lines).
> Hunk #2 FAILED at 658.
> 1 out of 2 hunks FAILED -- rejects in file fs/ext4/file.c

Here you go.

					- Ted

>From 9bb648f3a9a41adac5d345b7a0c7308e17dbf3a9 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Thu, 24 Aug 2017 13:22:06 -0400
Subject: [PATCH] ext4: in ext4_seek_{hole,data}, return -ENXIO for negative
 offsets

[ Upstream commit 1bd8d6cd3e413d64e543ec3e69ff43e75a1cf1ea ]

In the ext4 implementations of SEEK_HOLE and SEEK_DATA, make sure we
return -ENXIO for negative offsets instead of banging around inside
the extent code and returning -EFSCORRUPTED.

Reported-by: Mateusz S <muttdini@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org # 4.6
---
 fs/ext4/file.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index d17d12ed6f73..510e66422f04 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -527,7 +527,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 	inode_lock(inode);
 
 	isize = i_size_read(inode);
-	if (offset >= isize) {
+	if (offset < 0 || offset >= isize) {
 		inode_unlock(inode);
 		return -ENXIO;
 	}
@@ -590,7 +590,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 	inode_lock(inode);
 
 	isize = i_size_read(inode);
-	if (offset >= isize) {
+	if (offset < 0 || offset >= isize) {
 		inode_unlock(inode);
 		return -ENXIO;
 	}
-- 
2.11.0.rc0.7.gbe5a750