Re: [Qemu-devel] [PATCH for v2.4.1] exec: fix a glitch in checking dma r/w access

[P J P <ppandit@redhat.com>]

  Hello Paolo,

+-- On Mon, 25 Jan 2016, Paolo Bonzini wrote --+
| This should be handled correctly by address_space_translate_internal:
| 
|     if (memory_region_is_ram(mr)) {
|         diff = int128_sub(section->size, int128_make64(addr));
|         *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
|     }
| 
| ... then, on return from address_space_translate, l will be 1:
| 
|     e.g.  section->size = 0x100000000, addr = 0xffffffff;
|           diff = 1;
|           *plen = min(diff, *plen) = min(1, 4) = 1

  I see. Sorry, I think the issue affects versions <= v2.3.1 and not v2.4.x. 
v2.3.x series seems to be missing this patch

  -> http://git.qemu.org/?p=qemu.git;a=commit;h=23820dbfc79d1c9dce090b4c555994f2bb6a69b3

which avoids setting '*plen' to its earlier value. I'll send it to the -stable 
list.

| You also have to test that the patch doesn't break other code.  It's not
| enough to test that it solves your problem.

  Right, I'll run the tests/* going forward.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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