af_key: relax availability checks for skb size calculation

xfrm_probe_algs() probes kernel crypto modules and changes the
availability of struct xfrm_algo_desc. But there is a small window
where ealg->available and aalg->available get changed between
count_ah_combs()/count_esp_combs() and dump_ah_combs()/dump_esp_combs(),
in this case we may allocate a smaller skb but later put a larger
amount of data and trigger the panic in skb_put().

Fix this by relaxing the checks when counting the size, that is,
skipping the test of ->available. We may waste some memory for a few
of sizeof(struct sadb_comb), but it is still much better than a panic.

Reported-by: [email protected]
Cc: Steffen Klassert <[email protected]>
Cc: Herbert Xu <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
Signed-off-by: Steffen Klassert <[email protected]>

0 files changed, 0 insertions, 0 deletions