x86, tls, ldt: Stop checking lm in LDT_empty

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commit e30ab185c4 upstream.

32-bit programs don't have an lm bit in their ABI, so they can't
reliably cause LDT_empty to return true without resorting to memset.
They shouldn't need to do this.

This should fix a longstanding, if minor, issue in all 64-bit kernels
as well as a potential regression in the TLS hardening code.

Fixes: 41bdc78544 x86/tls: Validate TLS entries to protect espfix
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/72a059de55e86ad5e2935c80aa91880ddf19d07c.1421954363.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

...

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Andy Lutomirski 2015-01-22 11:27:58 -08:00 • committed by Luis Henriques

parent 67772bcaf0

commit ccda157ea1

1 changed files with 2 additions and 7 deletions

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arch/x86/include/asm/desc.h

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