Re: [PATCH] x86: Fix 32-bit compatible userspace write size overflow error

[H. Peter Anvin]

It's not clear to me that this is actually the correct behavior; the 
important thing is that it faults (as nothing is mapped above 4 GB anyway.)

	-hpa


On 11/15/23 02:56, Jinjie Ruan wrote:
> For 32-bit compatible userspace program, write with size = -1 return not
> -1 but unexpected other values, which is due to the __access_ok() check is
> insufficient. The specified "ptr + size" is greater than 32-bit limit and
> should return -EFAULT, but it is not checked and can not catch the overflow
> error.
>
> Fix above error by checking 32-bit limit if it is 32-bit compatible
> userspace program.

	-hpa