mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-18 17:54:13 +08:00
1027b96ec9
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: Minmin chen <chenmingmin@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
69 lines
1.5 KiB
C
69 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/slab.h>
|
|
#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)
|
|
{
|
|
struct once_work *work;
|
|
|
|
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 void once_disable_jump(struct static_key_true *key, struct module *mod)
|
|
{
|
|
struct once_work *w;
|
|
|
|
w = kmalloc(sizeof(*w), GFP_ATOMIC);
|
|
if (!w)
|
|
return;
|
|
|
|
INIT_WORK(&w->work, once_deferred);
|
|
w->key = key;
|
|
w->module = mod;
|
|
__module_get(mod);
|
|
schedule_work(&w->work);
|
|
}
|
|
|
|
static DEFINE_SPINLOCK(once_lock);
|
|
|
|
bool __do_once_start(bool *done, unsigned long *flags)
|
|
__acquires(once_lock)
|
|
{
|
|
spin_lock_irqsave(&once_lock, *flags);
|
|
if (*done) {
|
|
spin_unlock_irqrestore(&once_lock, *flags);
|
|
/* Keep sparse happy by restoring an even lock count on
|
|
* this lock. In case we return here, we don't call into
|
|
* __do_once_done but return early in the DO_ONCE() macro.
|
|
*/
|
|
__acquire(once_lock);
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(__do_once_start);
|
|
|
|
void __do_once_done(bool *done, struct static_key_true *once_key,
|
|
unsigned long *flags, struct module *mod)
|
|
__releases(once_lock)
|
|
{
|
|
*done = true;
|
|
spin_unlock_irqrestore(&once_lock, *flags);
|
|
once_disable_jump(once_key, mod);
|
|
}
|
|
EXPORT_SYMBOL(__do_once_done);
|