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x86-32, espfix: Remove filter for espfix32 due to race

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commit 246f2d2ee1 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 <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H. Peter Anvin
2014-04-30 14:03:25 -07:00
committed by Greg Kroah-Hartman
parent 43507abd62
commit 7a1d06c866
1 changed files with 0 additions and 5 deletions
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5
arch/x86/kernel/entry_32.S
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@@ -554,11 +554,6 @@ ENTRY(iret_exc)
CFI_RESTORE_STATE
ldt_ss:
larl PT_OLDSS(%esp), %eax
jnz restore_nocheck
testl $0x00400000, %eax # returning to 32bit stack?
jnz restore_nocheck # allright, normal return
#ifdef CONFIG_PARAVIRT
/*
* The kernel can't run on a non-flat stack if paravirt mode