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Date: Thu, 20 Feb 2014 18:44:59 +0100 From: Mateusz Guzik <mguzik@...hat.com> To: linux-kernel@...r.kernel.org Cc: Rik van Riel <riel@...hat.com> Subject: [PATCH] kref: oops on zero or negative refcount In use after free situations, it is possible for one thread to write to memory that has just been reallocated to a new user. This could open up potential security issues. Close off those potential security holes by terminating the current thread when kref encounters such a race condition or underflow. Signed-off-by: Mateusz Guzik <mguzik@...hat.com> Cc: Rik van Riel <riel@...hat.com> --- include/linux/kref.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/kref.h b/include/linux/kref.h index 484604d..c3f8a0a 100644 --- a/include/linux/kref.h +++ b/include/linux/kref.h @@ -43,8 +43,10 @@ static inline void kref_get(struct kref *kref) /* If refcount was 0 before incrementing then we have a race * condition when this kref is freeing by some other thread right now. * In this case one should use kref_get_unless_zero() + * + * Terminate the current thread to stop potential security exploits. */ - WARN_ON_ONCE(atomic_inc_return(&kref->refcount) < 2); + BUG_ON(atomic_inc_return(&kref->refcount) < 2); } /** -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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