[openssl-dev] [openssl.org #4545] Crash in crypto/rand/md_rand.c

[Matt Caswell via RT]

On 17/06/16 19:43, Mick Saxton via RT wrote:
> Perhaps we should consider if there are any negative consequences to my solution?
> It does work.
> 
> I am trying really hard to get contention but I am only seeing this problem in about 1 out of 100,000 successful TLSv1.2 connections
> On a heavily congested network.
> I require three machines to just to run the test that causes the failure.
> 
> All we are trying to do is get a random number – surely getting a slightly less random number is better than crashing?
> It could be that the problematic instances were going to disconnect anyway due to TCP/IP problems.
> 

I think we need to try instrumenting the code to see if we can get some
more information out. I will try and pull something together - but it
might be Monday before I get the opportunity.

Matt


> 
> 
> Rather than my previous suggestion – I am now suggesting:-
> 
> So in ssleay_rand_add
> 
>     If ( j-k>0 ) MD_Update(&m, &(state[st_idx]), j – k);
> 
> And a similar fix in ssleay_rand_bytes
> 
> 
> This also avoids adding zero bytes to the hash – which it does quite often.
> 
> 
> 
> 
> From: Salz, Rich via RT [mailto:rt at openssl.org]
> Sent: 17 June 2016 18:39
> To: Mick Saxton
> Cc: openssl-dev at openssl.org
> Subject: RE: [openssl-dev] [openssl.org #4545] Crash in crypto/rand/md_rand.c
> 
> Sending mail re-opens the ticket.
> 
> Rats, wish it was fixed. Going to need something to more easily reproduce it, I guess.
> 
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