From: Kefeng Wang wangkefeng.wang@huawei.com
[ Upstream commit 1027b96ec9d34f9abab69bc1a4dc5b1ad8ab1349 ]
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.c...
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 --- include/linux/once.h | 4 ++-- lib/once.c | 11 ++++++++--- 2 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/include/linux/once.h b/include/linux/once.h index 9225ee6d96c7..ae6f4eb41cbe 100644 --- a/include/linux/once.h +++ b/include/linux/once.h @@ -7,7 +7,7 @@
bool __do_once_start(bool *done, unsigned long *flags); void __do_once_done(bool *done, struct static_key_true *once_key, - unsigned long *flags); + unsigned long *flags, struct module *mod);
/* Call a function exactly once. The idea of DO_ONCE() is to perform * a function call such as initialization of random seeds, etc, only @@ -46,7 +46,7 @@ void __do_once_done(bool *done, struct static_key_true *once_key, if (unlikely(___ret)) { \ func(__VA_ARGS__); \ __do_once_done(&___done, &___once_key, \ - &___flags); \ + &___flags, THIS_MODULE); \ } \ } \ ___ret; \ diff --git a/lib/once.c b/lib/once.c index 8b7d6235217e..59149bf3bfb4 100644 --- a/lib/once.c +++ b/lib/once.c @@ -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) @@ -16,10 +18,11 @@ 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 void once_disable_jump(struct static_key_true *key) +static void once_disable_jump(struct static_key_true *key, struct module *mod) { struct once_work *w;
@@ -29,6 +32,8 @@ 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); }
@@ -53,11 +58,11 @@ bool __do_once_start(bool *done, unsigned long *flags) EXPORT_SYMBOL(__do_once_start);
void __do_once_done(bool *done, struct static_key_true *once_key, - unsigned long *flags) + unsigned long *flags, struct module *mod) __releases(once_lock) { *done = true; spin_unlock_irqrestore(&once_lock, *flags); - once_disable_jump(once_key); + once_disable_jump(once_key, mod); } EXPORT_SYMBOL(__do_once_done);