Re: [PATCH 1/2] ext4: Remove arbitrary block value in __es_remove_extent()

Theodore Ts'o
2014-04-17T16:19:47Z

On Tue, Apr 15, 2014 at 08:08:21PM +0200, Lukas Czerner wrote:
> In __es_remove_extent() we're storing seemingly arbitrary value
> 0x7FDEADBEEF into block variable. I assume that the reason is just to
> initialize the variable before the use because the actual value does not
> matter at this point.
>
> Just remove the arbitrary value and initialized block variable to zero
> which is much less suspicious.

The whole point was for the value to be suspicious. That way, if
there is a bug, and we try to use that value, it is a large enough
value that for most storage devices, we will get an I/O error (because
the disk isn't that big :-) referencing that block value, and we'll
have a bit of a hint where that suspicious value might have come from.

- Ted