[PATCH v3] sfc: falcon: potential dereference null pointer of rx_queue->page_ring

The return value of kcalloc() needs to be checked.
To avoid dereference of null pointer in case of the failure of alloc,
such as ef4_fini_rx_queue().
Therefore, it should be better to change the definition of page_ptr_mask
to signed int and then assign the page_ptr_mask to -1 when page_ring is
NULL, in order to avoid the use in the loop.

Fixes: 5a6681e22c14 ("sfc: separate out SFC4000 ("Falcon") support into new sfc-falcon driver")
Signed-off-by: Jiasheng Jiang <redacted>
---
Changelog:

v2 -> v3

*Change 1. Alter the "ret" to 'rc' and cleanup the rx_queue and tx_queue when alloc fails.
*Change 2. Set size to -1 instead of return error.
---
 drivers/net/ethernet/sfc/falcon/net_driver.h | 2 +-
 drivers/net/ethernet/sfc/falcon/rx.c         | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/sfc/falcon/net_driver.h b/drivers/net/ethernet/sfc/falcon/net_driver.h
index a381cf9ec4f3..2990563c8832 100644
--- a/drivers/net/ethernet/sfc/falcon/net_driver.h
+++ b/drivers/net/ethernet/sfc/falcon/net_driver.h

@@ -345,7 +345,7 @@ struct ef4_rx_queue {
 	unsigned int page_recycle_count;
 	unsigned int page_recycle_failed;
 	unsigned int page_recycle_full;
-	unsigned int page_ptr_mask;
+	int page_ptr_mask;
 	unsigned int max_fill;
 	unsigned int fast_fill_trigger;
 	unsigned int min_fill;

diff --git a/drivers/net/ethernet/sfc/falcon/rx.c b/drivers/net/ethernet/sfc/falcon/rx.c
index 966f13e7475d..328ad0685f59 100644
--- a/drivers/net/ethernet/sfc/falcon/rx.c
+++ b/drivers/net/ethernet/sfc/falcon/rx.c

@@ -728,7 +728,10 @@ static void ef4_init_rx_recycle_ring(struct ef4_nic *efx,
 					    efx->rx_bufs_per_page);
 	rx_queue->page_ring = kcalloc(page_ring_size,
 				      sizeof(*rx_queue->page_ring), GFP_KERNEL);
-	rx_queue->page_ptr_mask = page_ring_size - 1;
+	if (!rx_queue->page_ring)
+		rx_queue->page_ptr_mask = -1;
+	else
+		rx_queue->page_ptr_mask = page_ring_size - 1;
 }
 
 void ef4_init_rx_queue(struct ef4_rx_queue *rx_queue)

-- 
2.25.1