This is a note to let you know that I've just added the patch titled
x86, smap: smap_violation() is bogus if CONFIG_X86_SMAP is off
to the 3.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-smap-smap_violation-is-bogus-if-config_x86_smap-is-off.patch
and it can be found in the queue-3.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4640c7ee9b8953237d05a61ea3ea93981d1bc961 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@xxxxxxxxxxxxxxx>
Date: Thu, 13 Feb 2014 07:46:04 -0800
Subject: x86, smap: smap_violation() is bogus if CONFIG_X86_SMAP is off
From: "H. Peter Anvin" <hpa@xxxxxxxxxxxxxxx>
commit 4640c7ee9b8953237d05a61ea3ea93981d1bc961 upstream.
If CONFIG_X86_SMAP is disabled, smap_violation() tests for conditions
which are incorrect (as the AC flag doesn't matter), causing spurious
faults.
The dynamic disabling of SMAP (nosmap on the command line) is fine
because it disables X86_FEATURE_SMAP, therefore causing the
static_cpu_has() to return false.
Found by Fengguang Wu's test system.
[ v3: move all predicates into smap_violation() ]
[ v2: use IS_ENABLED() instead of #ifdef ]
Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhost
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/fault.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1001,6 +1001,12 @@ static int fault_in_kernel_space(unsigne
static inline bool smap_violation(int error_code, struct pt_regs *regs)
{
+ if (!IS_ENABLED(CONFIG_X86_SMAP))
+ return false;
+
+ if (!static_cpu_has(X86_FEATURE_SMAP))
+ return false;
+
if (error_code & PF_USER)
return false;
@@ -1087,11 +1093,9 @@ __do_page_fault(struct pt_regs *regs, un
if (unlikely(error_code & PF_RSVD))
pgtable_bad(regs, error_code, address);
- if (static_cpu_has(X86_FEATURE_SMAP)) {
- if (unlikely(smap_violation(error_code, regs))) {
- bad_area_nosemaphore(regs, error_code, address);
- return;
- }
+ if (unlikely(smap_violation(error_code, regs))) {
+ bad_area_nosemaphore(regs, error_code, address);
+ return;
}
/*
Patches currently in stable-queue which might be from hpa@xxxxxxxxxxxxxxx are
queue-3.13/x86-smap-smap_violation-is-bogus-if-config_x86_smap-is-off.patch
queue-3.13/x86-smap-don-t-enable-smap-if-config_x86_smap-is-disabled.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html