From: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> [ Upstream commit fc70f5bf5e525dde81565f0a30d5e39168062eba ] During rmnet unregistration, the real device rx_handler is first cleared followed by the removal of rx_handler_data after the rcu synchronization. Any packets in the receive path may observe that the rx_handler is NULL. However, there is no check when dereferencing this value to use the rmnet_port information. This fixes following splat by adding the NULL check. Unable to handle kernel NULL pointer dereference at virtual address 000000000000000d pc : rmnet_rx_handler+0x124/0x284 lr : rmnet_rx_handler+0x124/0x284 rmnet_rx_handler+0x124/0x284 __netif_receive_skb_core+0x758/0xd74 __netif_receive_skb+0x50/0x17c process_backlog+0x15c/0x1b8 napi_poll+0x88/0x284 net_rx_action+0xbc/0x23c __do_softirq+0x20c/0x48c Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation") Signed-off-by: Sean Tranchetti <stranche@codeaurora.org> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Link: https://lore.kernel.org/r/1605298325-3705-1-git-send-email-subashab@codeauro... Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c index c9d43bad1e2f..9b1804a228d9 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c @@ -197,6 +197,11 @@ rx_handler_result_t rmnet_rx_handler(struct sk_buff **pskb) dev = skb->dev; port = rmnet_get_port_rcu(dev); + if (unlikely(!port)) { + atomic_long_inc(&skb->dev->rx_nohandler); + kfree_skb(skb); + goto done; + } switch (port->rmnet_mode) { case RMNET_EPMODE_VND: -- 2.25.1