From: Nadav Amit <namit@cs.technion.ac.il>
Date: Wed, 19 Nov 2014 15:43:09 +0000 (+0200)
Subject: KVM: x86: Stack size is overridden by __linearize
X-Git-Tag: omap-for-v3.19/fixes-rc1~43^2~52
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1c1c35ae4b75d6fc08393a1f73a5a06dc68eebb8;p=pandora-kernel.git

KVM: x86: Stack size is overridden by __linearize

When performing segmented-read/write in the emulator for stack operations, it
ignores the stack size, and uses the ad_bytes as indication for the pointer
size. As a result, a wrong address may be accessed.

To fix this behavior, we can remove the masking of address in __linearize and
perform it beforehand.  It is already done for the operands (so currently it is
inefficiently done twice). It is missing in two cases:
1. When using rip_relative
2. On fetch_bit_operand that changes the address.

This patch masks the address on these two occassions, and removes the masking
from __linearize.

Note that it does not mask EIP during fetch. In protected/legacy mode code
fetch when RIP >= 2^32 should result in #GP and not wrap-around. Since we make
limit checks within __linearize, this is the expected behavior.

Partial revert of commit 518547b32ab4 (KVM: x86: Emulator does not
calculate address correctly, 2014-09-30).

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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