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

Brian Foster
2015-10-09T13:24:44Z

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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