From: Bjorn Andersson bjorn.andersson@linaro.org
commit 47a017f33943278570c072bc71681809b2567b3a upstream.
It is possible that the MHI ul_callback will be invoked immediately following the queueing of the skb for transmission, leading to the callback decrementing the refcount of the associated sk and freeing the skb.
As such the dereference of skb and the increment of the sk refcount must happen before the skb is queued, to avoid the skb to be used after free and potentially the sk to drop its last refcount..
Fixes: 6e728f321393 ("net: qrtr: Add MHI transport layer") Signed-off-by: Bjorn Andersson bjorn.andersson@linaro.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/qrtr/mhi.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/net/qrtr/mhi.c +++ b/net/qrtr/mhi.c @@ -50,6 +50,9 @@ static int qcom_mhi_qrtr_send(struct qrt struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev, ep); int rc;
+ if (skb->sk) + sock_hold(skb->sk); + rc = skb_linearize(skb); if (rc) goto free_skb; @@ -59,12 +62,11 @@ static int qcom_mhi_qrtr_send(struct qrt if (rc) goto free_skb;
- if (skb->sk) - sock_hold(skb->sk); - return rc;
free_skb: + if (skb->sk) + sock_put(skb->sk); kfree_skb(skb);
return rc;