Re: [PATCH 1/2] xfs_repair: initialize realloced bplist in longform_dir2_entry_check

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, Oct 22, 2018 at 11:04:31PM -0500, Eric Sandeen wrote:
> If we need to realloc the bplist[] array holding buffers for a given
> directory, we don't initialize the new slots.  This causes a problem
> if the directory has holes, because those slots never get filled in.
> 
> At the end of the function we call libxfs_putbuf for every non-null
> slot, and any uninitialized slots are segfault landmines.
> 
> Make sure we initialize all new slots to NULL for this reason.
> 
> Reported-by: Oleg Davydov <burunduk3@gmail.com>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Yay realloc :P

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> 
> diff --git a/repair/phase6.c b/repair/phase6.c
> index b87c751..9d24a4f 100644
> --- a/repair/phase6.c
> +++ b/repair/phase6.c
> @@ -2348,6 +2348,8 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
>  
>  		db = xfs_dir2_da_to_db(mp->m_dir_geo, da_bno);
>  		if (db >= num_bps) {
> +			int last_size = num_bps;
> +
>  			/* more data blocks than expected */
>  			num_bps = db + 1;
>  			bplist = realloc(bplist, num_bps * sizeof(struct xfs_buf*));
> @@ -2355,6 +2357,9 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
>  				do_error(_("realloc failed in %s (%zu bytes)\n"),
>  					__func__,
>  					num_bps * sizeof(struct xfs_buf*));
> +			/* Initialize the new elements */
> +			for (i = last_size; i < num_bps; i++)
> +				bplist[i] = NULL;
>  		}
>  
>  		if (isblock)
>