Re: [oss-security] CVE-2026-31431: CopyFail: linux local privilege scalation

[Demi Marie Obenour]

On 5/2/26 15:13, Richard Kettlewell wrote:
> On 01/05/2026 16:30, Demi Marie Obenour wrote:
>> On 4/30/26 03:19, Eric Biggers wrote:
>>> But I also hope this finally provides some more impetus for AF_ALG to be
>>> deprecated and removed.  It's a massive, largely pointless attack
>>> surface which has been causing problems, including regular CVEs, ever
>>> since it was added to the kernel in 2010.  And of course it's gotten
>>> even worse lately, with LLMs now being able to find the bugs.
>>>
>>> Userspace crypto libraries exist.  There's no need to escalate to kernel
>>> mode just to do some math.
>>
>> The only reason I can think of to keep it is for embedded systems
>> with weak CPUs and crypto accelerators that are actually worth using.
>> However, those seem to be very rare outside of things like routers,
>> which run specialized distros like OpenWRT.  Even when the accelerator
>> exists and is worth using, AF_ALG is certainly not an efficient way
>> to access it.
> 
> I have that use case, although fortunately it's in a context where 
> splice() is disabled. But the requirement is for access to the SoC's 
> accelerator - the interface doesn't need to be via AF_ALG in particular, 
> it doesn't have to offer software crypto (and it might be better if it 
> didn't), and it needn't be independent of the specific hardware 
> (although in the bigger picture it'd be a shame if it wasn't).
> 
> ttfn/rjk

Can you provide benchmarks showing that the accelerator is faster
than the CPU on realistic workloads?
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)

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