Re: [Qemu-devel] [PATCH] linux-user: fix ipc(SEMCTL, ...) argument handling

[Paul Burton <paul@archlinuxmips.org>]

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On Mon, Jun 23, 2014 at 11:12:42PM +0100, Peter Maydell wrote:
> On 23 June 2014 22:40, Paul Burton <paul@archlinuxmips.org> wrote:
> > The ptr argument to the ipc syscall was incorrectly being used as the
> > value of the argument union for the SEMCTL call. It is actually, as its
> > name would suggest, a pointer to that union.
> 
> Have you checked this on other architectures than MIPS?
> I have a vague recollection that there are between-arch
> differences regarding handling of the semctl argument...

I haven't tried running code for any other targets, but the pointer is
dereferenced from generic code in Linux, see ipc/syscall.c:

  http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/ipc/syscall.c#n39
 
> Also, VERIFY_READ doesn't seem right for some of the
> semctl operations which will modify the target_semun.
> 
> thanks
> -- PMM

That part I think you're right about, I'll switch to VERIFY_WRITE.

Thanks,
    Paul

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