In the Linux kernel, the following vulnerability has been resolved:
xfrm: fix xfrm_state_construct() auth-trunc leak
attach_auth_trunc() can allocate x->aalg while leaving
x->props.aalgo at zero when the selected auth algorithm has no
sadb_alg_id. One real case is cmac(aes).
xfrm_state_construct() then treats !x->props.aalgo as "no auth
algorithm attached yet" and calls attach_auth(). That overwrites
x->aalg and loses the first allocation. Any later failure or teardown
only frees the replacement pointer.
Check whether x->aalg is already attached instead of inferring that
state from x->props.aalgo.