linux-kernel - Re: [PATCH] xfs: check for negatives in xfs_exchange_range

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Message-ID: <ZjrVaynGeygNaDtQ@dread.disaster.area>
Date: Wed, 8 May 2024 11:29:15 +1000
From: Dave Chinner <david@...morbit.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: "Darrick J. Wong" <djwong@...nel.org>,
	Chandan Babu R <chandan.babu@...cle.com>, linux-xfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] xfs: check for negatives in xfs_exchange_range_checks()

On Sat, May 04, 2024 at 02:27:36PM +0300, Dan Carpenter wrote:
> The fxr->file1_offset and fxr->file2_offset variables come from the user
> in xfs_ioc_exchange_range().  They are size loff_t which is an s64.
> Check the they aren't negative.
> 
> Fixes: 9a64d9b3109d ("xfs: introduce new file range exchange ioctl")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
> From static analysis.  Untested.  Sorry!
> 
>  fs/xfs/xfs_exchrange.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/xfs/xfs_exchrange.c b/fs/xfs/xfs_exchrange.c
> index c8a655c92c92..3465e152d928 100644
> --- a/fs/xfs/xfs_exchrange.c
> +++ b/fs/xfs/xfs_exchrange.c
> @@ -337,6 +337,9 @@ xfs_exchange_range_checks(
>  	if (IS_SWAPFILE(inode1) || IS_SWAPFILE(inode2))
>  		return -ETXTBSY;
>  
> +	if (fxr->file1_offset < 0 || fxr->file2_offset < 0)
> +		return -EINVAL;

Aren't the operational offset/lengths already checked for underflow
and overflow via xfs_exchange_range_verify_area()?

-Dave.
-- 
Dave Chinner
david@...morbit.com