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once: Fix panic when module unload
[ Upstream commit 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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
f68ad168e2
commit
6815e21fe2
2 changed files with 10 additions and 5 deletions
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@ -7,7 +7,7 @@
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bool __do_once_start(bool *done, unsigned long *flags);
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bool __do_once_start(bool *done, unsigned long *flags);
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void __do_once_done(bool *done, struct static_key_true *once_key,
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void __do_once_done(bool *done, struct static_key_true *once_key,
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unsigned long *flags);
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unsigned long *flags, struct module *mod);
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/* Call a function exactly once. The idea of DO_ONCE() is to perform
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/* Call a function exactly once. The idea of DO_ONCE() is to perform
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* a function call such as initialization of random seeds, etc, only
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* a function call such as initialization of random seeds, etc, only
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@ -46,7 +46,7 @@ void __do_once_done(bool *done, struct static_key_true *once_key,
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if (unlikely(___ret)) { \
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if (unlikely(___ret)) { \
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func(__VA_ARGS__); \
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func(__VA_ARGS__); \
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__do_once_done(&___done, &___once_key, \
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__do_once_done(&___done, &___once_key, \
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&___flags); \
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&___flags, THIS_MODULE); \
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} \
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} \
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} \
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} \
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___ret; \
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___ret; \
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11
lib/once.c
11
lib/once.c
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@ -3,10 +3,12 @@
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#include <linux/spinlock.h>
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#include <linux/spinlock.h>
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#include <linux/once.h>
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#include <linux/once.h>
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#include <linux/random.h>
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#include <linux/random.h>
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#include <linux/module.h>
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struct once_work {
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struct once_work {
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struct work_struct work;
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struct work_struct work;
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struct static_key_true *key;
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struct static_key_true *key;
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struct module *module;
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};
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};
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static void once_deferred(struct work_struct *w)
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static void once_deferred(struct work_struct *w)
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@ -16,10 +18,11 @@ static void once_deferred(struct work_struct *w)
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work = container_of(w, struct once_work, work);
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work = container_of(w, struct once_work, work);
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BUG_ON(!static_key_enabled(work->key));
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BUG_ON(!static_key_enabled(work->key));
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static_branch_disable(work->key);
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static_branch_disable(work->key);
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module_put(work->module);
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kfree(work);
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kfree(work);
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}
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}
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static void once_disable_jump(struct static_key_true *key)
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static void once_disable_jump(struct static_key_true *key, struct module *mod)
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{
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{
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struct once_work *w;
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struct once_work *w;
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@ -29,6 +32,8 @@ static void once_disable_jump(struct static_key_true *key)
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INIT_WORK(&w->work, once_deferred);
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INIT_WORK(&w->work, once_deferred);
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w->key = key;
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w->key = key;
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w->module = mod;
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__module_get(mod);
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schedule_work(&w->work);
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schedule_work(&w->work);
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}
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}
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@ -53,11 +58,11 @@ bool __do_once_start(bool *done, unsigned long *flags)
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EXPORT_SYMBOL(__do_once_start);
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EXPORT_SYMBOL(__do_once_start);
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void __do_once_done(bool *done, struct static_key_true *once_key,
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void __do_once_done(bool *done, struct static_key_true *once_key,
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unsigned long *flags)
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unsigned long *flags, struct module *mod)
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__releases(once_lock)
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__releases(once_lock)
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{
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{
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*done = true;
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*done = true;
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spin_unlock_irqrestore(&once_lock, *flags);
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spin_unlock_irqrestore(&once_lock, *flags);
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once_disable_jump(once_key);
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once_disable_jump(once_key, mod);
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}
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}
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EXPORT_SYMBOL(__do_once_done);
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EXPORT_SYMBOL(__do_once_done);
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