[S35,13/15] ice: add extra check for null rx descriptor
diff mbox series

Message ID 20191212111307.33566-13-anthony.l.nguyen@intel.com
State Accepted
Delegated to: Jeff Kirsher
Headers show
Series
  • [S35,01/15] ice: Support UDP segmentation offload
Related show

Commit Message

Tony Nguyen Dec. 12, 2019, 11:13 a.m. UTC
From: Mitch Williams <mitch.a.williams@intel.com>

In the case where the hardware gives us a null rx descriptor, it is
theoretically possible that we could call one of our skb-construction
functions with no data pointer, which would cause a panic.

In real life, this will never happen - we only get null RX
descriptors as the final descriptor in a chain of otherwise-valid
descriptors. When this happens, the skb will be extant and we'll just
call ice_add_rx_frag(), which can deal with empty data buffers.

Unfortunately, Coverity does not have intimate knowledge of our
hardware, so we must add a check here.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_txrx.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

Comments

Bowers, AndrewX Dec. 18, 2019, 10:32 p.m. UTC | #1
> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On
> Behalf Of Tony Nguyen
> Sent: Thursday, December 12, 2019 3:13 AM
> To: intel-wired-lan@lists.osuosl.org
> Subject: [Intel-wired-lan] [PATCH S35 13/15] ice: add extra check for null rx
> descriptor
> 
> From: Mitch Williams <mitch.a.williams@intel.com>
> 
> In the case where the hardware gives us a null rx descriptor, it is theoretically
> possible that we could call one of our skb-construction functions with no data
> pointer, which would cause a panic.
> 
> In real life, this will never happen - we only get null RX descriptors as the final
> descriptor in a chain of otherwise-valid descriptors. When this happens, the
> skb will be extant and we'll just call ice_add_rx_frag(), which can deal with
> empty data buffers.
> 
> Unfortunately, Coverity does not have intimate knowledge of our hardware,
> so we must add a check here.
> 
> Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
> ---
>  drivers/net/ethernet/intel/ice/ice_txrx.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)

Tested-by: Andrew Bowers <andrewx.bowers@intel.com>

Patch
diff mbox series

diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
index b77514bbd7ba..fd17ace6b226 100644
--- a/drivers/net/ethernet/intel/ice/ice_txrx.c
+++ b/drivers/net/ethernet/intel/ice/ice_txrx.c
@@ -1071,13 +1071,16 @@  static int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
 		ice_put_rx_buf(rx_ring, rx_buf);
 		continue;
 construct_skb:
-		if (skb)
+		if (skb) {
 			ice_add_rx_frag(rx_ring, rx_buf, skb, size);
-		else if (ice_ring_uses_build_skb(rx_ring))
-			skb = ice_build_skb(rx_ring, rx_buf, &xdp);
-		else
+		} else if (likely(xdp.data)) {
+			if (ice_ring_uses_build_skb(rx_ring))
+				skb = ice_build_skb(rx_ring, rx_buf, &xdp);
+			else
+				skb = ice_construct_skb(rx_ring, rx_buf, &xdp);
+		} else {
 			skb = ice_construct_skb(rx_ring, rx_buf, &xdp);
-
+		}
 		/* exit if we failed to retrieve a buffer */
 		if (!skb) {
 			rx_ring->rx_stats.alloc_buf_failed++;