From: H. Peter Anvin Date: Wed, 30 Apr 2014 21:03:25 +0000 (-0700) Subject: x86-32, espfix: Remove filter for espfix32 due to race X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=246f2d2ee1d715e1077fc47d61c394569c8ee692;p=linux-beck.git x86-32, espfix: Remove filter for espfix32 due to race 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 Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com Cc: # consider after upstream merge --- diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index a2a4f4697889..2780b8f3b96c 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -551,11 +551,6 @@ 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