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Elena Reshetova
17ac99b2b8
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable mlx4_srq.refcount is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <[email protected]> Reviewed-by: David Windsor <[email protected]> Reviewed-by: Hans Liljestrand <[email protected]> Signed-off-by: Elena Reshetova <[email protected]> Signed-off-by: David S. Miller <[email protected]>