Commit e8dd2d2d641c ("Silence compiler warning in arch/x86/kvm/emulate.c",
2015-09-06) broke boot of the Hurd. The bug is that the "default:"
case actually could modify "la", but after the patch this change is
not reflected in *linear.
The bug is visible whenever a non-zero segment base causes the linear
address to wrap around the 4GB mark.
Fixes: e8dd2d2d641cb2724ee10e76c0ad02e04289c017
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Aurelien Jarno <aurelien@xxxxxxxxxxx>
Tested-by: Aurelien Jarno <aurelien@xxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 1505587d06e9..b9b09fec173b 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -650,10 +650,10 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
u16 sel;
la = seg_base(ctxt, addr.seg) + addr.ea;
- *linear = la;
*max_size = 0;
switch (mode) {
case X86EMUL_MODE_PROT64:
+ *linear = la;
if (is_noncanonical_address(la))
goto bad;
@@ -662,6 +662,7 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
goto bad;
break;
default:
+ *linear = la = (u32)la;
usable = ctxt->ops->get_segment(ctxt, &sel, &desc, NULL,
addr.seg);
if (!usable)
@@ -689,7 +690,6 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
if (size > *max_size)
goto bad;
}
- la &= (u32)-1;
break;
}
if (insn_aligned(ctxt, size) && ((la & (size - 1)) != 0))
--
1.8.3.1
--
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