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[Qemu-devel] Re: [PATCH 1/2] Fix segfault in mmio subpage handling code.
From: |
Marcelo Tosatti |
Subject: |
[Qemu-devel] Re: [PATCH 1/2] Fix segfault in mmio subpage handling code. |
Date: |
Thu, 29 Jul 2010 18:16:40 -0300 |
User-agent: |
Mutt/1.5.20 (2009-08-17) |
On Thu, Jul 29, 2010 at 01:41:45PM +0300, Gleb Natapov wrote:
> Use this one instead.
>
> On Wed, Jul 28, 2010 at 06:13:22PM +0300, Gleb Natapov wrote:
> > It is possible that subpage mmio is registered over existing memory
> > page. When this happens "memory" will have real memory address and not
> > index into io_mem array so next access to the page will generate
> > segfault. It is uncommon to have some part of a page to be accessed as
> > memory and some as mmio, but qemu shouldn't crash even when guest does
> > stupid things. So lets just pretend that the rest of the page is
> > unassigned if guest configure part of the memory page as mmio.
> >
> > Signed-off-by: Gleb Natapov <address@hidden>
>
> diff --git a/exec.c b/exec.c
> index 5e9a5b7..53483bc 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -3362,6 +3362,8 @@ static int subpage_register (subpage_t *mmio, uint32_t
> start, uint32_t end,
> printf("%s: %p start %08x end %08x idx %08x eidx %08x mem %ld\n",
> __func__,
> mmio, start, end, idx, eidx, memory);
> #endif
> + if ((memory & ~TARGET_PAGE_MASK) == IO_MEM_RAM)
> + memory = IO_MEM_UNASSIGNED;
> memory = (memory >> IO_MEM_SHIFT) & (IO_MEM_NB_ENTRIES - 1);
> for (; idx <= eidx; idx++) {
> mmio->sub_io_index[idx] = memory;
Looks good to me.