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Commit 23eb8e37 authored by 王克锋's avatar 王克锋 Committed by Yang Yingliang
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once: Fix panic when module unload

hulk inclusion
category: bugfix
bugzilla: 172153
CVE: NA

-------------------------------------------------

DO_ONCE
DEFINE_STATIC_KEY_TRUE(___once_key);
__do_once_done
  once_disable_jump(once_key);
    INIT_WORK(&w->work, once_deferred);
    struct once_work *w;
    w->key = key;
    schedule_work(&w->work);                     module unload
                                                   //*the key is destroy*
process_one_work
  once_deferred
    BUG_ON(!static_key_enabled(work->key));
       static_key_count((struct static_key *)x)    //*access key, crash*

When module uses DO_ONCE mechanism, it could crash due to the above
concurrency problem, we could reproduce it with link[1].

Fix it by add/put module refcount in the once work process.

[1]
https://lore.kernel.org/netdev/eaa6c371-465e-57eb-6be9-f4b16b9d7cbf@huawei.com/



Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Reported-by: default avatarMinmin chen <chenmingmin@huawei.com>
Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
parent 3d5dba2f
No related branches found
Tags 4.19.90-2107.1.0
No related merge requests found
......@@ -3,10 +3,12 @@
#include <linux/spinlock.h>
#include <linux/once.h>
#include <linux/random.h>
#include <linux/module.h>
struct once_work {
struct work_struct work;
struct static_key_true *key;
struct module *module;
};
static void once_deferred(struct work_struct *w)
......@@ -16,11 +18,24 @@ static void once_deferred(struct work_struct *w)
work = container_of(w, struct once_work, work);
BUG_ON(!static_key_enabled(work->key));
static_branch_disable(work->key);
module_put(work->module);
kfree(work);
}
static struct module *find_module_by_key(struct static_key_true *key)
{
struct module *mod;
preempt_disable();
mod = __module_address((unsigned long)key);
preempt_enable();
return mod;
}
static void once_disable_jump(struct static_key_true *key)
{
struct module *mod = find_module_by_key(key);
struct once_work *w;
w = kmalloc(sizeof(*w), GFP_ATOMIC);
......@@ -29,6 +44,8 @@ static void once_disable_jump(struct static_key_true *key)
INIT_WORK(&w->work, once_deferred);
w->key = key;
w->module = mod;
__module_get(mod);
schedule_work(&w->work);
}
......
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