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Re: [PATCH 3/5] xfs_logprint: fix some unaligned accesses

To: Eric Sandeen <sandeen@xxxxxxxxxxx>
Subject: Re: [PATCH 3/5] xfs_logprint: fix some unaligned accesses
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Fri, 9 Oct 2015 16:08:27 -0400
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <56181AF0.7090904@xxxxxxxxxxx>
References: <56181A17.9080503@xxxxxxxxxxx> <56181AF0.7090904@xxxxxxxxxxx>
User-agent: Mutt/1.5.23 (2014-03-12)
On Fri, Oct 09, 2015 at 02:52:16PM -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@xxxxxxxxxx>
> ---
> 
> V2: Change variable scope, remove extraneous hunk
> 

Thanks!

Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>

>  logprint/log_misc.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/logprint/log_misc.c b/logprint/log_misc.c
> index d76145c..4cdcbec 100644
> --- a/logprint/log_misc.c
> +++ b/logprint/log_misc.c
> @@ -243,9 +243,6 @@ int
>  xlog_print_trans_buffer(char **ptr, int len, int *i, int num_ops)
>  {
>      xfs_buf_log_format_t *f;
> -    xfs_agi_t                 *agi;
> -    xfs_agf_t                 *agf;
> -    xfs_disk_dquot_t  *dq;
>      xlog_op_header_t  *head = NULL;
>      int                       num, skip;
>      int                       super_block = 0;
> @@ -325,7 +322,11 @@ 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, agi_s;
> +
> +             /* memmove because *ptr may not be 8-byte aligned */
> +             agi = &agi_s;
> +             memmove(agi, *ptr, sizeof(struct xfs_agi));
>               printf(_("AGI Buffer: XAGI  "));
>               /*
>                * v4 filesystems only contain the fields before the uuid.
> @@ -375,7 +376,11 @@ xlog_print_trans_buffer(char **ptr, int len, int *i, int 
> num_ops)
>                       }
>               }
>       } else if (be32_to_cpu(*(__be32 *)(*ptr)) == XFS_AGF_MAGIC) {
> -             agf = (xfs_agf_t *)(*ptr);
> +             struct xfs_agf  *agf, agf_s;
> +
> +             /* memmove because *ptr may not be 8-byte aligned */
> +             agf = &agf_s;
> +             memmove(agf, *ptr, sizeof(struct xfs_agf));
>               printf(_("AGF Buffer: XAGF  "));
>               /*
>                * v4 filesystems only contain the fields before the uuid.
> @@ -408,7 +413,11 @@ xlog_print_trans_buffer(char **ptr, int len, int *i, int 
> num_ops)
>                               be32_to_cpu(agf->agf_longest));
>               }
>       } else if (be32_to_cpu(*(__be32 *)(*ptr)) == XFS_DQUOT_MAGIC) {
> -             dq = (xfs_disk_dquot_t *)(*ptr);
> +             struct xfs_disk_dquot *dq, dq_s;
> +
> +             /* memmove because *ptr may not be 8-byte aligned */
> +             dq = &dq_s;
> +             memmove(dq, *ptr, sizeof(struct xfs_disk_dquot));
>               printf(_("DQUOT Buffer: DQ  "));
>               if (be32_to_cpu(head->oh_len) <
>                               sizeof(xfs_disk_dquot_t)) {
> -- 
> 2.6.1
> 
> 
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