Re: [PATCH] KVM: x86 emulator: Fix unconditional return from get_descriptor_table_ptr()

[Avi Kivity]

On 05/21/2011 07:06 AM, Takuya Yoshikawa wrote:

From: Takuya Yoshikawayoshikawa.tak...@oss.ntt.co.jp

A trivial typo was found in the following commit:
   commit 7753ed6043bfce55dc0c407490896632014b677e
   KVM: x86 emulator: drop vcpu argument from segment/gdt/idt callbacks

When the table indicator flag is set, when the selector selects the
current LDT, get_descriptor_table_ptr() returns without setting the
size and address of the table.

Guests will see #GP if this happens.



Thanks, applied.


Signed-off-by: Takuya Yoshikawayoshikawa.tak...@oss.ntt.co.jp
---
  Is this stable material? -- IIRC, someone reported a suspicous
  emulator bug recently.


This was not yet merged upstream, so I folded this into the bad commit, 
and upstream will never see the bug.  It's now 4bff1e86ad286d in kvm.git.


--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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[PATCH] KVM: x86 emulator: Fix unconditional return from get_descriptor_table_ptr()

[Takuya Yoshikawa]

From: Takuya Yoshikawa yoshikawa.tak...@oss.ntt.co.jp

A trivial typo was found in the following commit:
  commit 7753ed6043bfce55dc0c407490896632014b677e
  KVM: x86 emulator: drop vcpu argument from segment/gdt/idt callbacks

When the table indicator flag is set, when the selector selects the
current LDT, get_descriptor_table_ptr() returns without setting the
size and address of the table.

Guests will see #GP if this happens.

Signed-off-by: Takuya Yoshikawa yoshikawa.tak...@oss.ntt.co.jp
---
 Is this stable material? -- IIRC, someone reported a suspicous
 emulator bug recently.

 arch/x86/kvm/emulate.c |2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3bc6b7a..b8b9748 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1158,7 +1158,7 @@ static void get_descriptor_table_ptr(struct 
x86_emulate_ctxt *ctxt,
u16 sel;
 
memset (dt, 0, sizeof *dt);
-   if (!ops-get_segment(ctxt, sel, desc, NULL, VCPU_SREG_LDTR));
+   if (!ops-get_segment(ctxt, sel, desc, NULL, VCPU_SREG_LDTR))
return;
 
dt-size = desc_limit_scaled(desc); /* what if limit  65535? 
*/
-- 
1.7.4.1

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