lkml.org 
[lkml]   [2015]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
Subject[RFC] kvm - possible out of bounds
From
Hello,

I have found a possible out of bounds reading in
arch/powerpc/kvm/book3s_64_mmu.c (kvmppc_mmu_book3s_64_xlate
function). pteg[] array could be accessed twice using the i variable
after the for iteration. What happens is that in the last iteration
the i index is incremented to 16, checked (i<16) then confirmed
exiting the loop.

277 for (i=0; i<16; i+=2) { ...

Later there are reading attempts to the pteg last elements, but using
again the already incremented i (16).

303 v = be64_to_cpu(pteg[i]); /* pteg[16] */
304 r = be64_to_cpu(pteg[i+1]); /* pteg[17] */

I really don't know if the for lace will somehow iterate until i is
16, anyway I think that the last readings must be using a defined max
len/index or another more clear method.

Eg.

v = be64_to_cpu(pteg[PTEG_LEN - 2]);
r = be64_to_cpu(pteg[PTEG_LEN - 1]);

Or just.

v = be64_to_cpu(pteg[14]);
r = be64_to_cpu(pteg[15]);

----------------------------

I found in the same file a variable that is not used.

380 struct kvmppc_vcpu_book3s *vcpu_book3s;
...
387 vcpu_book3s = to_book3s(vcpu);

-----------------------------

A question, the kvmppc_mmu_book3s_64_init function is accessed by
unconventional way? Because I have not found any calling to it.

If something that I wrote is correct please tell me if I could send the patch.

--
Regards,

Geyslan G. Bem
hackingbits.com


\
 
 \ /
  Last update: 2015-11-29 21:41    [W:0.043 / U:0.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site