Re: [PATCH 2/4] livepatch: Handle failing allocation of shadow variables in the selftest

[Petr Mladek]

On Mon 2019-01-21 17:40:12, Joe Lawrence wrote:
> On Wed, Jan 16, 2019 at 05:17:18PM +0100, Petr Mladek wrote:
> > Do not dereference pointers to the shadow variables when either
> > klp_shadow_alloc() or klp_shadow_get() fail.
> > 
> > There is no need to check the other locations explicitly. The test
> > would fail if any allocation fails. And the existing messages, printed
> > during the test, provide enough information to debug eventual problems.
> > 
> 
> I didn't run the test under those failing conditions, but at looking at
> the code, I think it would simply skip the "expected <conditions> found"
> and the test script would complain about not seeing that msg.

Accessing an invalid pointer would crash the kernel.


> Would it be easier to just bite the bullet and verify sv[0-4] at their
> allocation sites?  Then later uses (ie, the sv3 dereference that
> Miroslav spotted at the bottom) or new code wouldn't fall through the
> cracks.

As I wrote in the replay to Miroslav. The best practice is to
handle errors everywhere. I am going to do so in v2. People
might use it as a sample...

Best Regards,
Petr