115 lines
3.3 KiB
Diff
115 lines
3.3 KiB
Diff
From b3b7c4795ccab5be71f080774c45bbbcc75c2aaf Mon Sep 17 00:00:00 2001
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From: Seunghun Han <kkamagui@gmail.com>
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Date: Tue, 6 Mar 2018 15:21:43 +0100
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Subject: [PATCH] x86/MCE: Serialize sysfs changes
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The check_interval file in
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/sys/devices/system/machinecheck/machinecheck<cpu number>
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directory is a global timer value for MCE polling. If it is changed by one
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CPU, mce_restart() broadcasts the event to other CPUs to delete and restart
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the MCE polling timer and __mcheck_cpu_init_timer() reinitializes the
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mce_timer variable.
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If more than one CPU writes a specific value to the check_interval file
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concurrently, mce_timer is not protected from such concurrent accesses and
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all kinds of explosions happen. Since only root can write to those sysfs
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variables, the issue is not a big deal security-wise.
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However, concurrent writes to these configuration variables is void of
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reason so the proper thing to do is to serialize the access with a mutex.
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Boris:
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- Make store_int_with_restart() use device_store_ulong() to filter out
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negative intervals
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- Limit min interval to 1 second
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- Correct locking
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- Massage commit message
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Signed-off-by: Seunghun Han <kkamagui@gmail.com>
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Signed-off-by: Borislav Petkov <bp@suse.de>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Cc: Tony Luck <tony.luck@intel.com>
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Cc: linux-edac <linux-edac@vger.kernel.org>
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Cc: stable@vger.kernel.org
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Link: http://lkml.kernel.org/r/20180302202706.9434-1-kkamagui@gmail.com
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---
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arch/x86/kernel/cpu/mcheck/mce.c | 22 +++++++++++++++++++++-
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1 file changed, 21 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
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index b3323cab9139..466f47301334 100644
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--- a/arch/x86/kernel/cpu/mcheck/mce.c
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+++ b/arch/x86/kernel/cpu/mcheck/mce.c
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@@ -56,6 +56,9 @@
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static DEFINE_MUTEX(mce_log_mutex);
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+/* sysfs synchronization */
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+static DEFINE_MUTEX(mce_sysfs_mutex);
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+
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#define CREATE_TRACE_POINTS
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#include <trace/events/mce.h>
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@@ -2088,6 +2091,7 @@ static ssize_t set_ignore_ce(struct device *s,
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if (kstrtou64(buf, 0, &new) < 0)
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return -EINVAL;
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+ mutex_lock(&mce_sysfs_mutex);
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if (mca_cfg.ignore_ce ^ !!new) {
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if (new) {
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/* disable ce features */
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@@ -2100,6 +2104,8 @@ static ssize_t set_ignore_ce(struct device *s,
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on_each_cpu(mce_enable_ce, (void *)1, 1);
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}
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}
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+ mutex_unlock(&mce_sysfs_mutex);
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+
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return size;
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}
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@@ -2112,6 +2118,7 @@ static ssize_t set_cmci_disabled(struct device *s,
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if (kstrtou64(buf, 0, &new) < 0)
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return -EINVAL;
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+ mutex_lock(&mce_sysfs_mutex);
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if (mca_cfg.cmci_disabled ^ !!new) {
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if (new) {
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/* disable cmci */
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@@ -2123,6 +2130,8 @@ static ssize_t set_cmci_disabled(struct device *s,
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on_each_cpu(mce_enable_ce, NULL, 1);
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}
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}
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+ mutex_unlock(&mce_sysfs_mutex);
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+
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return size;
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}
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@@ -2130,8 +2139,19 @@ static ssize_t store_int_with_restart(struct device *s,
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struct device_attribute *attr,
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const char *buf, size_t size)
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{
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- ssize_t ret = device_store_int(s, attr, buf, size);
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+ unsigned long old_check_interval = check_interval;
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+ ssize_t ret = device_store_ulong(s, attr, buf, size);
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+
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+ if (check_interval == old_check_interval)
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+ return ret;
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+
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+ if (check_interval < 1)
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+ check_interval = 1;
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+
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+ mutex_lock(&mce_sysfs_mutex);
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mce_restart();
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+ mutex_unlock(&mce_sysfs_mutex);
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+
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return ret;
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}
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--
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2.14.3
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