Re: [PATCH] xfs: fix null pointer dereference in tracepoint

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Jul 09, 2026 at 11:41:16AM +0200, Andrey Albershteyn wrote:
> If dfp is not NULL we exit early here, when dfp is NULL it's allocated
> in xfs_defer_alloc() but not assigned. The tracepoint tries to
> dereference members of dfp struct.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>

Heh, I have a patch just like this too!  Please add:

Cc: <stable@vger.kernel.org> # v6.8
Fixes: 3f3cec031099c3 ("xfs: force small EFIs for reaping btree extents")
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/libxfs/xfs_defer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
> index c6909716b041..89501e8bd2f8 100644
> --- a/fs/xfs/libxfs/xfs_defer.c
> +++ b/fs/xfs/libxfs/xfs_defer.c
> @@ -878,7 +878,7 @@ xfs_defer_add_barrier(
>  	if (dfp)
>  		return;
>  
> -	xfs_defer_alloc(&tp->t_dfops, &xfs_barrier_defer_type);
> +	dfp = xfs_defer_alloc(&tp->t_dfops, &xfs_barrier_defer_type);
>  
>  	trace_xfs_defer_add_item(tp->t_mountp, dfp, NULL);
>  }
> -- 
> 2.54.0
> 
>