Re: [PATCH 1/4] xfs_db: don't print arrays off the end of a buffer

[Eric Sandeen <sandeen@sandeen.net>]

On 4/10/17 5:47 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Before printing an array, clamp the array count against the size of the
> buffer so that we don't print random heap contents.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  db/print.c |   11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> 
> diff --git a/db/print.c b/db/print.c
> index e31372f..0caad8f 100644
> --- a/db/print.c
> +++ b/db/print.c
> @@ -144,6 +144,17 @@ print_flist_1(
>  			if (fl->flags & FL_OKHIGH)
>  				count = min(count, fl->high - low + 1);
>  			if (fa->prfunc) {
> +				int	fsz;
> +				int	bitlen;
> +
> +				/* Don't read an array off the end of the buffer */
> +				fsz = fsize(f, iocur_top->data, parentoff, 0);
> +				bitlen = iocur_top->len * NBBY;
> +				if ((f->flags & FLD_ARRAY) &&
> +				    fl->offset + (count * fsz) > bitlen) {
> +					count = (bitlen - fl->offset) / fsz;
> +				}
> +
>  				neednl = fa->prfunc(iocur_top->data, fl->offset,
>  					count, fa->fmtstr,
>  					fsize(f, iocur_top->data, parentoff, 0),

can we just re-use fsz here in the prfunc call?

Otherwise seems fine, and I could do that on commit.

Reviewed-by: Eric Sandeen <sandeen@redhat.com>

> 
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