On Tue, Feb 24, 2015 at 2:52 PM, H. Peter Anvin <[email protected]> wrote: > On 02/24/2015 02:25 PM, Andy Lutomirski wrote: >> On Tue, Feb 24, 2015 at 10:51 AM, Denys Vlasenko <[email protected]> wrote: >>> In all three 32-bit entry points, %eax is zero-extended to %rax. >>> It is safe to do 32-bit compare when checking that syscall# >>> is not too large. >> >> Applied. Thanks! >> > > NAK NAK NAK NAK NAK!!!! > > We have already had this turn into a security issue not just once but > TWICE, because someone decided to "optimize" the path by taking out the > zero extend. > > The use of a 64-bit compare here is an intentional "belts and > suspenders" safety issue.
Fair enough. OK if I just undo that part of this patch? --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
