Re: [PATCH v2] platform/x86/amd/pmf: Use memdup_user()

[Thorsten Blum]

Hi Dan,

On 27. May 2024, at 12:38, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> Also this check isn't great:
> 
> if (dev->policy_sz < header->length + 512)
> 
> header->length is a u32 that comes from the user, so the addition can
> overflow.  I can't immediately see how to exploit this though since we
> don't seem to use header->length after this (by itself).

How about

	if (header->length > U32_MAX - 512 || dev->policy_sz < header->length + 512)
		return -EINVAL;

to prevent a possible overflow?

header->length is used in the next line

	dev->policy_sz = header->length + 512;

and if the addition overflows, we end up setting dev->policy_sz to an 
invalid value.

Thanks,
Thorsten