On Fri, Aug 07, 2009 at 02:57:39PM -0400, Jeff Layton wrote:
> If fiemap_check_ranges is passed a large enough value, then it's
> possible that the value would be cast to a signed value for comparison
> against s_maxbytes when we change it to loff_t. Make sure that doesn't
> happen by explicitly casting s_maxbytes to an unsigned value for the
> purposes of comparison.
I think this is unneeded, C garuantees that in this case the signed
value will get promoted to an unsigned value, not the other way round.
Hannes
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/ioctl.c | 9 +++++----
> 1 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 5612880..7b17a14 100644
> --- a/fs/ioctl.c
> +++ b/fs/ioctl.c
> @@ -162,20 +162,21 @@ EXPORT_SYMBOL(fiemap_check_flags);
> static int fiemap_check_ranges(struct super_block *sb,
> u64 start, u64 len, u64 *new_len)
> {
> + u64 maxbytes = (u64) sb->s_maxbytes;
> +
> *new_len = len;
>
> if (len == 0)
> return -EINVAL;
>
> - if (start > sb->s_maxbytes)
> + if (start > maxbytes)
> return -EFBIG;
>
> /*
> * Shrink request scope to what the fs can actually handle.
> */
> - if ((len > sb->s_maxbytes) ||
> - (sb->s_maxbytes - len) < start)
> - *new_len = sb->s_maxbytes - start;
> + if (len > maxbytes || (maxbytes - len) < start)
> + *new_len = maxbytes - start;
>
> return 0;
> }
> --
> 1.6.0.6
>
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