Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.13 106/162] KVM: x86: Fix far-jump to non-canonical check | Date | Thu, 6 Nov 2014 14:36:10 -0800 |
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3.13.11.11 -stable review patch. If anyone has any objections, please let me know.
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From: Nadav Amit <namit@cs.technion.ac.il>
commit 7e46dddd6f6cd5dbf3c7bd04a7e75d19475ac9f2 upstream.
Commit d1442d85cc30 ("KVM: x86: Handle errors when RIP is set during far jumps") introduced a bug that caused the fix to be incomplete. Due to incorrect evaluation, far jump to segment with L bit cleared (i.e., 32-bit segment) and RIP with any of the high bits set (i.e, RIP[63:32] != 0) set may not trigger #GP. As we know, this imposes a security problem.
In addition, the condition for two warnings was incorrect.
Fixes: d1442d85cc30ea75f7d399474ca738e0bc96f715 Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> [Add #ifdef CONFIG_X86_64 to avoid complaints of undefined behavior. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [ kamal: backport to 3.13-stable: omitted WARN_ON fixes (not in 3.13) ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/x86/kvm/emulate.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index a440bea..4ae37e7 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -581,12 +581,14 @@ static inline int assign_eip_far(struct x86_emulate_ctxt *ctxt, ulong dst, case 4: ctxt->_eip = (u32)dst; break; +#ifdef CONFIG_X86_64 case 8: if ((cs_l && is_noncanonical_address(dst)) || - (!cs_l && (dst & ~(u32)-1))) + (!cs_l && (dst >> 32) != 0)) return emulate_gp(ctxt, 0); ctxt->_eip = dst; break; +#endif default: WARN(1, "unsupported eip assignment size\n"); } -- 1.9.1
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