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Patch "genirq: Fix race in register_irq_proc()" has been added to the 3.10-stable tree

PATCH [email protected] 1 participant 1 message Oct 18, 2015

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This is a note to let you know that I've just added the patch titled

genirq: Fix race in register_irq_proc()

to the 3.10-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:
genirq-fix-race-in-register_irq_proc.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 95c2b17534654829db428f11bcf4297c059a2a7e Mon Sep 17 00:00:00 2001

From: Ben Hutchings <[email protected]>
Date: Sat, 26 Sep 2015 12:23:56 +0100
Subject: genirq: Fix race in register_irq_proc()

From: Ben Hutchings <[email protected]>

commit 95c2b17534654829db428f11bcf4297c059a2a7e upstream.

Per-IRQ directories in procfs are created only when a handler is first added to the irqdesc, not when the irqdesc is created. In the case of a shared IRQ, multiple tasks can race to create a directory. This race condition seems to have been present forever, but is easier to hit with async probing.

Signed-off-by Ben Hutchings <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Thomas Gleixner <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 kernel/irq/proc.c |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)
kernel/irq/proc.c +17 -2
@@ -12,6 +12,7 @@
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
+#include <linux/mutex.h>
 
 #include "internals.h"
 

@@ -309,18 +310,29 @@ void register_handler_proc(unsigned int
 
 void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
+	static DEFINE_MUTEX(register_lock);
 	char name [MAX_NAMELEN];
 
-	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip) || desc->dir)
+	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip))
 		return;
 
+	/*
+	 * irq directories are registered only when a handler is
+	 * added, not when the descriptor is created, so multiple
+	 * tasks might try to register at the same time.
+	 */
+	mutex_lock(&register_lock);
+
+	if (desc->dir)
+		goto out_unlock;
+
 	memset(name, 0, MAX_NAMELEN);
 	sprintf(name, "%d", irq);
 
 	/* create /proc/irq/1234 */
 	desc->dir = proc_mkdir(name, root_irq_dir);
 	if (!desc->dir)
-		return;
+		goto out_unlock;
 
 #ifdef CONFIG_SMP
 	/* create /proc/irq/<irq>/smp_affinity */

@@ -341,6 +353,9 @@ void register_irq_proc(unsigned int irq,
 
 	proc_create_data("spurious", 0444, desc->dir,
 			 &irq_spurious_proc_fops, (void *)(long)irq);
+
+out_unlock:
+	mutex_unlock(&register_lock);
 }
 
 void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)

Patches currently in stable-queue which might be from [email protected] are

queue-3.10/genirq-fix-race-in-register_irq_proc.patch queue-3.10/bonding-correct-the-mac-address-for-follow-fail_over_mac-policy.patch