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

[Paul Burton]

On Mon, Jun 23, 2014 at 11:18:25PM +0100, Paul Burton wrote:
> > 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.

Actually no, I don't think you're right about that afterall. The
argument union itself is never modified. I imagine if it were then it
would be painful in the case of the semctl syscall where the union is
passed directly as an argument, rather than as a pointer as it is for
the ipc syscall.

What may be modified is the data pointed to by the pointers within union
semun. That is already handled by do_semctl & the translate functions it
calls.

/me is not fond of this API...

So anyway, I believe the patch is good as-is.

Thanks,
    Paul

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