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Subject[PATCH 3.4 32/43] x86-32, espfix: Remove filter for espfix32 due to race
3.4-stable review patch.  If anyone has any objections, please let me know.


From: "H. Peter Anvin" <>

commit 246f2d2ee1d715e1077fc47d61c394569c8ee692 upstream.

It is not safe to use LAR to filter when to go down the espfix path,
because the LDT is per-process (rather than per-thread) and another
thread might change the descriptors behind our back. Fortunately it
is always *safe* (if a bit slow) to go down the espfix path, and a
32-bit LDT stack segment is extremely rare.

Signed-off-by: H. Peter Anvin <>
Signed-off-by: Greg Kroah-Hartman <>

arch/x86/kernel/entry_32.S | 5 -----
1 file changed, 5 deletions(-)

--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -550,11 +550,6 @@ ENTRY(iret_exc)

- larl PT_OLDSS(%esp), %eax
- jnz restore_nocheck
- testl $0x00400000, %eax # returning to 32bit stack?
- jnz restore_nocheck # allright, normal return
* The kernel can't run on a non-flat stack if paravirt mode

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