The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 12ac1d0f6c3e95732d144ffa65c8b20fbd9aa462 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Tue, 5 Sep 2017 10:12:20 +0200
Subject: [PATCH] genirq: Make sparse_irq_lock protect what it should protect
for_each_active_irq() iterates the sparse irq allocation bitmap. The caller
must hold sparse_irq_lock. Several code pathes expect that an active bit in
the sparse bitmap also has a valid interrupt descriptor.
Unfortunately that's not true. The (de)allocation is a two step process,
which holds the sparse_irq_lock only across the queue/remove from the radix
tree and the set/clear in the allocation bitmap.
If a iteration locks sparse_irq_lock between the two steps, then it might
see an active bit but the corresponding irq descriptor is NULL. If that is
dereferenced unconditionally, then the kernel oopses. Of course, all
iterator sites could be audited and fixed, but....
There is no reason why the sparse_irq_lock needs to be dropped between the
two steps, in fact the code becomes simpler when the mutex is held across
both and the semantics become more straight forward, so future problems of
missing NULL pointer checks in the iteration are avoided and all existing
sites are fixed in one go.
Expand the lock held sections so both operations are covered and the bitmap
and the radixtree are in sync.
Fixes: a05a900a51c7 ("genirq: Make sparse_lock a mutex")
Reported-and-tested-by: Huang Ying <ying.huang@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 73be2b3909bd..82afb7ed369f 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -421,10 +421,8 @@ static void free_desc(unsigned int irq)
* The sysfs entry must be serialized against a concurrent
* irq_sysfs_init() as well.
*/
- mutex_lock(&sparse_irq_lock);
kobject_del(&desc->kobj);
delete_irq_desc(irq);
- mutex_unlock(&sparse_irq_lock);
/*
* We free the descriptor, masks and stat fields via RCU. That
@@ -462,20 +460,15 @@ static int alloc_descs(unsigned int start, unsigned int cnt, int node,
desc = alloc_desc(start + i, node, flags, mask, owner);
if (!desc)
goto err;
- mutex_lock(&sparse_irq_lock);
irq_insert_desc(start + i, desc);
irq_sysfs_add(start + i, desc);
- mutex_unlock(&sparse_irq_lock);
}
+ bitmap_set(allocated_irqs, start, cnt);
return start;
err:
for (i--; i >= 0; i--)
free_desc(start + i);
-
- mutex_lock(&sparse_irq_lock);
- bitmap_clear(allocated_irqs, start, cnt);
- mutex_unlock(&sparse_irq_lock);
return -ENOMEM;
}
@@ -575,6 +568,7 @@ static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
desc->owner = owner;
}
+ bitmap_set(allocated_irqs, start, cnt);
return start;
}
@@ -670,10 +664,10 @@ void irq_free_descs(unsigned int from, unsigned int cnt)
if (from >= nr_irqs || (from + cnt) > nr_irqs)
return;
+ mutex_lock(&sparse_irq_lock);
for (i = 0; i < cnt; i++)
free_desc(from + i);
- mutex_lock(&sparse_irq_lock);
bitmap_clear(allocated_irqs, from, cnt);
mutex_unlock(&sparse_irq_lock);
}
@@ -720,19 +714,15 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
from, cnt, 0);
ret = -EEXIST;
if (irq >=0 && start != irq)
- goto err;
+ goto unlock;
if (start + cnt > nr_irqs) {
ret = irq_expand_nr_irqs(start + cnt);
if (ret)
- goto err;
+ goto unlock;
}
-
- bitmap_set(allocated_irqs, start, cnt);
- mutex_unlock(&sparse_irq_lock);
- return alloc_descs(start, cnt, node, affinity, owner);
-
-err:
+ ret = alloc_descs(start, cnt, node, affinity, owner);
+unlock:
mutex_unlock(&sparse_irq_lock);
return ret;
}