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

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Oct 10, 2017 at 05:44:25PM -0400, Theodore Ts'o wrote:
> 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;
>  	}

That worked, thanks!  All now applied.

greg k-h