Re: [PATCH 3/4] xfs_logprint: fix some unaligned accesses

[Brian Foster <bfoster@redhat.com>]

On Thu, Oct 08, 2015 at 07:25:50PM -0500, Eric Sandeen wrote:
> This routine had a fair bit of gyration to avoid unaligned accesses,
> but didn't fix them all.  Fix some more spotted at runtime by libubsan.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>  logprint/log_misc.c |   18 +++++++++++++++---
>  repair/btree.c      |    1 +
>  2 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/logprint/log_misc.c b/logprint/log_misc.c
> index d76145c..6cd249a 100644
> --- a/logprint/log_misc.c
> +++ b/logprint/log_misc.c
> @@ -325,7 +325,11 @@ xlog_print_trans_buffer(char **ptr, int len, int *i, int num_ops)
>  		}
>  		super_block = 0;
>  	} else if (be32_to_cpu(*(__be32 *)(*ptr)) == XFS_AGI_MAGIC) {
> -		agi = (xfs_agi_t *)(*ptr);
> +		struct xfs_agi agi_s;
> +
> +		/* memmove because *ptr may not be 8-byte aligned */
> +		memmove(&agi_s, *ptr, sizeof(struct xfs_agi));
> +		agi = &agi_s;

Nit: could we either define the new variables in the same scope as the
pointer (either here or at the top of the function), or just ditch the
pointers altogether?

>  		printf(_("AGI Buffer: XAGI  "));
>  		/*
>  		 * v4 filesystems only contain the fields before the uuid.
...
> diff --git a/repair/btree.c b/repair/btree.c
> index 66fb40b..e31e67a 100644
> --- a/repair/btree.c
> +++ b/repair/btree.c
> @@ -230,6 +230,7 @@ btree_get_next(
>  	}
>  	if (level == 0) {
>  		if (key) {
> +		/* XXXX what if index past MAX?  What if no next? */

Unintentional hunk?

Brian

>  			cur->index++;
>  			*key = btree_key_of_cursor(cur, root->height);
>  			cur->index--;
> -- 
> 1.7.1
> 
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