Re: [PATCH v2 0/2] block: Use 'read-zeroes=true' mode by default with 'null-co' driver

[Fam Zheng]

On 2021-02-19 15:09, Philippe Mathieu-Daudé wrote:
> On 2/19/21 12:07 PM, Max Reitz wrote:
> > On 13.02.21 22:54, Fam Zheng wrote:
> >> On 2021-02-11 15:26, Philippe Mathieu-Daudé wrote:
> >>> The null-co driver doesn't zeroize buffer in its default config,
> >>> because it is designed for testing and tests want to run fast.
> >>> However this confuses security researchers (access to uninit
> >>> buffers).
> >>
> >> I'm a little surprised.
> >>
> >> Is changing default the only way to fix this? I'm not opposed to
> >> changing the default but I'm not convinced this is the easiest way.
> >> block/nvme.c also doesn't touch the memory, but defers to the device
> >> DMA, why doesn't that confuse the security checker?
> 
> Generally speaking, there is a balance between security and performance.
> We try to provide both, but when we can't, my understanding is security
> is more important.

Why is hiding the code path behind a non-default more secure? What is
not secure now?

Fam