On 1/27/21 9:53 PM, Bob Pearson wrote:
> On 1/27/21 9:50 PM, Zhu Yanjun wrote:
>> On Thu, Jan 28, 2021 at 9:12 AM Bob Pearson <rpearsonhpe@xxxxxxxxx> wrote:
>>>
>>> rxe_rcv_mcast_pkt() in rxe_recv.c can leak SKBs in error path
>>> code. The loop over the QPs attached to a multicast group
>>> creates new cloned SKBs for all but the last QP in the list
>>> and passes the SKB and its clones to rxe_rcv_pkt() for further
>>> processing. Any QPs that do not pass some checks are skipped.
>>> If the last QP in the list fails the tests the SKB is leaked.
>>> This patch checks if the SKB for the last QP was used and if
>>> not frees it. Also removes a redundant loop invariant assignment.
>>>
>>> Fixes: 8700e3e7c4857 ("Soft RoCE driver")
>>> Fixes: 71abf20b28ff8 ("RDMA/rxe: Handle skb_clone() failure in rxe_recv.c")
>>> Signed-off-by: Bob Pearson <rpearson@xxxxxxx>
>>> ---
>>> drivers/infiniband/sw/rxe/rxe_recv.c | 18 +++++++++++-------
>>> 1 file changed, 11 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
>>> index c9984a28eecc..57cc25e3b4ad 100644
>>> --- a/drivers/infiniband/sw/rxe/rxe_recv.c
>>> +++ b/drivers/infiniband/sw/rxe/rxe_recv.c
>>> @@ -252,7 +252,6 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
>>>
>>> list_for_each_entry(mce, &mcg->qp_list, qp_list) {
>>> qp = mce->qp;
>>> - pkt = SKB_TO_PKT(skb);
>>>
>>> /* validate qp for incoming packet */
>>> err = check_type_state(rxe, pkt, qp);
>>> @@ -264,12 +263,18 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
>>> continue;
>>>
>>> /* for all but the last qp create a new clone of the
>>> - * skb and pass to the qp.
>>> + * skb and pass to the qp. If an error occurs in the
>>> + * checks for the last qp in the list we need to
>>> + * free the skb since it hasn't been passed on to
>>> + * rxe_rcv_pkt() which would free it later.
>>> */
>>> - if (mce->qp_list.next != &mcg->qp_list)
>>> + if (mce->qp_list.next != &mcg->qp_list) {
>>> per_qp_skb = skb_clone(skb, GFP_ATOMIC);
>>> - else
>>> + } else {
>>> per_qp_skb = skb;
>>> + /* show we have consumed the skb */
>>> + skb = NULL;
>>> + }
>>>
>>> if (unlikely(!per_qp_skb))
>>> continue;
>>> @@ -284,10 +289,9 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
>>>
>>> rxe_drop_ref(mcg); /* drop ref from rxe_pool_get_key. */
>>>
>>> - return;
>>> -
>>> err1:
>>> - kfree_skb(skb);
>>> + if (skb)
>>> + kfree_skb(skb);
>>
>> "if (skb)" is not needed here.
>>
>> The implemetation of kfree_skb:
>>
>> void kfree_skb(struct sk_buff *skb)
>> {
>> if (unlikely(!skb))
>> return;
>> if (likely(atomic_read(&skb->users) == 1))
>> smp_rmb();
>> else if (likely(!atomic_dec_and_test(&skb->users)))
>> return;
>> trace_kfree_skb(skb, __builtin_return_address(0));
>> __kfree_skb(skb);
>> }
>>
>> Zhu Yanjun
>>> }
>>>
>>> /**
>>> --
>>> 2.27.0
>>>
> Agreed but the reason I wrote that was to make it obvious why I set skb to NULL above. But as long as it is clear without it I can remove the test.
>
Actually I should have written
if (unlikely(skb))
kfree_skb(skb);
