Messages in this thread | | | Date | Sun, 29 Nov 2015 17:14:03 -0300 | Subject | [RFC] kvm - possible out of bounds | From | Geyslan Gregório Bem <> |
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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]);
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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);
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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
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