Re: [PATCH v2] x86: Fix x32 System V message queue syscalls

[Harald van Dijk]

On 06/12/2020 22:55, Andy Lutomirski wrote:
> On Sat, Dec 5, 2020 at 4:01 PM Jessica Clarke <jrtc27@xxxxxxxxxx> wrote:
> >
>
> > Ping?
>
> Can you submit patches implementing my proposal?  One is your existing
> patch plus fixing struct msghdr, with Cc: stable@xxxxxxxxxxxxxxx at
> the bottom.  The second is a removal of struct msghdr from uapi,
> moving it into include/inux (no uapi) if needed.  The second should
> not cc stable.

Hi,

This looks like it was forgotten, but it is still needed. Jessica, are 
you interested in submitting the requested change? If not, would it be 
okay if I do so? I have been running this locally for a long time now.

There is one complication that I think has not been mentioned yet: when 
_GNU_SOURCE is defined, glibc does provide a definition of struct msghdr 
in <sys/msg.h> with a field "__syscall_slong_t mtype;". This makes it 
slightly more likely that there is code out there in the wild that works 
fine with current kernels and would be broken by the fix. Given how rare 
x32 is, and how rare message queues are, this may still be acceptable, 
but I am mentioning it just in case this would cause a different 
approach to be preferred. And whatever is done, a fix should also be 
submitted to glibc.

(musl define struct msghdr as well, but defines mtype unconditionally as 
having type long, so if this approach is still preferred, needs no changes.)

Cheers,
Harald van Dijk