Re: [linuxsh-dev] Re: bad alignment fixup

[Jesper S. <js...@re...>]

>>>>> "Philipp" == Philipp Rumpf <pr...@pa...> writes:

Philipp> On Fri, Nov 24, 2000 at 09:15:39AM +0900, NIIBE Yutaka wrote:
>> Philipp Rumpf wrote: > On Thu, Nov 23, 2000 at 04:50:26PM +0000,
>> David Howells wrote: > > > user code to emulate unaligned accesses,
>> which can be written as someone > > > actually found a userspace
>> programs that needs them.  > > > > We have the code anyway to fix
>> up kernel accesses.  > > no.  we have the code for the few insns
>> actually used by the kernel, and it > can go away as soon as
>> someone convinced DaveM having the network stack use > unaligned
>> accesses is silly.
>> 
>> I also think that supporting kernel unaligned access is not good
>> idea, but Jesper said that DoS possibility (we should check), which
>> I care.

Philipp> We currently need kernel unaligned accesses for weird network
Philipp> protocols; there's also a remote exploit possibility.  As for
Philipp> the DoS, I think what Jesper meant was that if you do emulate
Philipp> unaligned accesses, userspace can keep doing
Philipp> kernel->user->kernel transitions, which is true anyway.

That's what I meant. But on second thought, I guess the exit path goes
past the schedule code, doesn't it? If so, it's not an issue. My
concern was if there was a separate path in and out of the kernel to
the fixup code - but that's probably not the case.

Jesper