cpumask: fix bug in use cpumask_var_t in irq_desc

Impact: fix bug where new irq_desc uses old cpumask pointers which are freed.

As Yinghai pointed out, init_copy_one_irq_desc() copies the old desc to
the new desc overwriting the cpumask pointers.  Since the old_desc and
the cpumask pointers are freed, then memory corruption will occur if
these old pointers are used.

Move the allocation of these pointers to after the copy.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Yinghai Lu <yinghai@kernel.org>

diff --git a/include/linux/irq.h b/include/linux/irq.h
index fa27210..27a6753 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -426,15 +426,18 @@ extern int set_irq_msi(unsigned int irq, struct msi_desc *entry);
 /**
  * init_alloc_desc_masks - allocate cpumasks for irq_desc
  * @desc:      pointer to irq_desc struct
+ * @cpu:       cpu which will be handling the cpumasks
  * @boot:      true if need bootmem
  *
  * Allocates affinity and pending_mask cpumask if required.
  * Returns true if successful (or not required).
  * Side effect: affinity has all bits set, pending_mask has all bits clear.
  */
-static inline bool init_alloc_desc_masks(struct irq_desc *desc, int node,
+static inline bool init_alloc_desc_masks(struct irq_desc *desc, int cpu,
                                                                bool boot)
 {
+       int node;
+
        if (boot) {
                alloc_bootmem_cpumask_var(&desc->affinity);
                cpumask_setall(desc->affinity);
@@ -446,6 +449,8 @@ static inline bool init_alloc_desc_masks(struct irq_desc *desc, int node,
                return true;
        }
 
+       node = cpu_to_node(cpu);
+
        if (!alloc_cpumask_var_node(&desc->affinity, GFP_ATOMIC, node))
                return false;
        cpumask_setall(desc->affinity);
@@ -484,7 +489,7 @@ static inline void init_copy_desc_masks(struct irq_desc *old_desc,
 
 #else /* !CONFIG_SMP */
 
-static inline bool init_alloc_desc_masks(struct irq_desc *desc, int node,
+static inline bool init_alloc_desc_masks(struct irq_desc *desc, int cpu,
                                                                bool boot)
 {
        return true;

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index b8fa135..f01c0a3 100644 (file)
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -85,8 +85,6 @@ void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
 
 static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
 {
-       int node = cpu_to_node(cpu);
-
        memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
 
        spin_lock_init(&desc->lock);
@@ -100,7 +98,7 @@ static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
                printk(KERN_ERR "can not alloc kstat_irqs\n");
                BUG_ON(1);
        }
-       if (!init_alloc_desc_masks(desc, node, false)) {
+       if (!init_alloc_desc_masks(desc, cpu, false)) {
                printk(KERN_ERR "can not alloc irq_desc cpumasks\n");
                BUG_ON(1);
        }
@@ -188,10 +186,6 @@ struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
                printk(KERN_ERR "can not alloc irq_desc\n");
                BUG_ON(1);
        }
-       if (!init_alloc_desc_masks(desc, node, false)) {
-               printk(KERN_ERR "can not alloc irq_desc cpumasks\n");
-               BUG_ON(1);
-       }
        init_one_irq_desc(irq, desc, cpu);
 
        irq_desc_ptrs[irq] = desc;

diff --git a/kernel/irq/numa_migrate.c b/kernel/irq/numa_migrate.c
index f001a4e..666260e 100644 (file)
--- a/kernel/irq/numa_migrate.c
+++ b/kernel/irq/numa_migrate.c
@@ -38,16 +38,22 @@ static void free_kstat_irqs(struct irq_desc *old_desc, struct irq_desc *desc)
        old_desc->kstat_irqs = NULL;
 }
 
-static void init_copy_one_irq_desc(int irq, struct irq_desc *old_desc,
+static bool init_copy_one_irq_desc(int irq, struct irq_desc *old_desc,
                 struct irq_desc *desc, int cpu)
 {
        memcpy(desc, old_desc, sizeof(struct irq_desc));
+       if (!init_alloc_desc_masks(desc, cpu, false)) {
+               printk(KERN_ERR "irq %d: can not get new irq_desc cpumask "
+                               "for migration.\n", irq);
+               return false;
+       }
        spin_lock_init(&desc->lock);
        desc->cpu = cpu;
        lockdep_set_class(&desc->lock, &irq_desc_lock_class);
        init_copy_kstat_irqs(old_desc, desc, cpu, nr_cpu_ids);
        init_copy_desc_masks(old_desc, desc);
        arch_init_copy_chip_data(old_desc, desc, cpu);
+       return true;
 }
 
 static void free_one_irq_desc(struct irq_desc *old_desc, struct irq_desc *desc)
@@ -83,15 +89,12 @@ static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc,
                desc = old_desc;
                goto out_unlock;
        }
-       if (!init_alloc_desc_masks(desc, node, false)) {
-               printk(KERN_ERR "irq %d: can not get new irq_desc cpumask "
-                               "for migration.\n", irq);
+       if (!init_copy_one_irq_desc(irq, old_desc, desc, cpu)) {
                /* still use old one */
                kfree(desc);
                desc = old_desc;
                goto out_unlock;
        }
-       init_copy_one_irq_desc(irq, old_desc, desc, cpu);
 
        irq_desc_ptrs[irq] = desc;