[PATCH net 3/4] sfc: null out channel->rps_flow_id after freeing it

[Edward Cree]

If an ef100_net_open() fails, ef100_net_stop() may be called without
 channel->rps_flow_id having been written; thus it may hold the address
 freed by a previous ef100_net_stop()'s call to efx_remove_filters().
 This then causes a double-free when efx_remove_filters() is called
 again, leading to a panic.
To prevent this, after freeing it, overwrite it with NULL.

Fixes: a9dc3d5612ce ("sfc_ef100: RX filter table management and related 
gubbins")
Signed-off-by: Edward Cree <ec...@solarflare.com>
---
 drivers/net/ethernet/sfc/rx_common.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/sfc/rx_common.c 
b/drivers/net/ethernet/sfc/rx_common.c
index ef9bca92b0b7..5e29284c89c9 100644
--- a/drivers/net/ethernet/sfc/rx_common.c
+++ b/drivers/net/ethernet/sfc/rx_common.c
@@ -849,6 +849,7 @@ void efx_remove_filters(struct efx_nic *efx)
        efx_for_each_channel(channel, efx) {
                cancel_delayed_work_sync(&channel->filter_work);
                kfree(channel->rps_flow_id);
+               channel->rps_flow_id = NULL;
        }
 #endif
        down_write(&efx->filter_sem);