| From | Luis Henriques <> | Subject | [PATCH 3.11 012/198] x86-32, espfix: Remove filter for espfix32 due to race | Date | Thu, 3 Jul 2014 10:17:35 +0100 |
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3.11.10.13 -stable review patch. If anyone has any objections, please let me know.
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From: "H. Peter Anvin" <hpa@linux.intel.com>
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 <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/x86/kernel/entry_32.S | 5 ----- 1 file changed, 5 deletions(-)
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index bbc89cf397bd..473f125a3a52 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -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 -- 1.9.1
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