This doesn't seem to fix a regression -- I don't think the CLAC was
ever there.
I double-checked in a debugger: entries through the int80 gate do
not automatically clear AC.
Stable maintainers: I can provide a backport to 4.3 and earlier if
needed. This needs to be backported all the way to 3.10.
Reported-by: Brian Gerst <brgerst@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 63bcff2a307b ("x86, smap: Add STAC and CLAC instructions to control user space access")
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
arch/x86/entry/entry_64_compat.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 5e887ee35662..41fbb3389a2f 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -261,6 +261,7 @@ ENTRY(entry_INT80_compat)
* Interrupts are off on entry.
*/
PARAVIRT_ADJUST_EXCEPTION_FRAME
+ ASM_CLAC /* Do this early to minimize exposure */
SWAPGS
/*
--
2.5.0
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