[PATCH v2 0/5] arm64: kernel: Add support for User Access Override

On 07/03/16 17:23, Russell King - ARM Linux wrote:

On Mon, Mar 07, 2016 at 04:43:19PM +0000, James Morse wrote:

quoted

As far as I can see, this would only affect arm64. I can't find an equivalent
memset() for x86_64.

I don't think you've looked hard enough. :)

Heh, Thanks! I ignored the 32bit code and instead got lost in the maze of
underscores and alternative-strings for the 64 bit path.

Having seen that path, I've now found:

/* If the destination is a kernel buffer, we always clear the end */
if (!__addr_ok(to))
	memset(to, 0, len);

in arch/x86/lib/usercopy_64.c:copy_user_handle_tail(), which may be the x86_64
equivalent, or I may be lost in the maze again.


Thanks!

James