[PATCH] net: atlantic: Fix NULL dereference of skb pointer in

[Daniil Maximov <daniil31415it@xxxxxxxxx>]

If is_ptp_ring == true in the loop of __aq_ring_xdp_clean function,
then a timestamp is stored from a packet in a field of skb object,
which is not allocated at the moment of the call (skb == NULL).

Generalize aq_ptp_extract_ts and other affected functions so they don't
work with struct sk_buff*, but with struct skb_shared_hwtstamps*.

Found by Linux Verification Center (linuxtesting.org) with SVACE

Fixes: 26efaef759a1 ("net: atlantic: Implement xdp data plane")
Signed-off-by: Daniil Maximov <daniil31415it@xxxxxxxxx>
---
 .../net/ethernet/aquantia/atlantic/aq_ptp.c    | 10 +++++-----
 .../net/ethernet/aquantia/atlantic/aq_ptp.h    |  4 ++--
 .../net/ethernet/aquantia/atlantic/aq_ring.c   | 18 ++++++++++++------
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c b/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c
index 80b44043e6c5..28c9b6f1a54f 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ptp.c
@@ -553,17 +553,17 @@ void aq_ptp_tx_hwtstamp(struct aq_nic_s *aq_nic, u64 timestamp)
 
 /* aq_ptp_rx_hwtstamp - utility function which checks for RX time stamp
  * @adapter: pointer to adapter struct
- * @skb: particular skb to send timestamp with
+ * @shhwtstamps: particular skb_shared_hwtstamps to save timestamp
  *
  * if the timestamp is valid, we convert it into the timecounter ns
  * value, then store that result into the hwtstamps structure which
  * is passed up the network stack
  */
-static void aq_ptp_rx_hwtstamp(struct aq_ptp_s *aq_ptp, struct sk_buff *skb,
+static void aq_ptp_rx_hwtstamp(struct aq_ptp_s *aq_ptp, struct skb_shared_hwtstamps *shhwtstamps,
 			       u64 timestamp)
 {
 	timestamp -= atomic_read(&aq_ptp->offset_ingress);
-	aq_ptp_convert_to_hwtstamp(aq_ptp, skb_hwtstamps(skb), timestamp);
+	aq_ptp_convert_to_hwtstamp(aq_ptp, shhwtstamps, timestamp);
 }
 
 void aq_ptp_hwtstamp_config_get(struct aq_ptp_s *aq_ptp,
@@ -639,7 +639,7 @@ bool aq_ptp_ring(struct aq_nic_s *aq_nic, struct aq_ring_s *ring)
 	       &aq_ptp->ptp_rx == ring || &aq_ptp->hwts_rx == ring;
 }
 
-u16 aq_ptp_extract_ts(struct aq_nic_s *aq_nic, struct sk_buff *skb, u8 *p,
+u16 aq_ptp_extract_ts(struct aq_nic_s *aq_nic, struct skb_shared_hwtstamps *shhwtstamps, u8 *p,
 		      unsigned int len)
 {
 	struct aq_ptp_s *aq_ptp = aq_nic->aq_ptp;
@@ -648,7 +648,7 @@ u16 aq_ptp_extract_ts(struct aq_nic_s *aq_nic, struct sk_buff *skb, u8 *p,
 						   p, len, &timestamp);
 
 	if (ret > 0)
-		aq_ptp_rx_hwtstamp(aq_ptp, skb, timestamp);
+		aq_ptp_rx_hwtstamp(aq_ptp, shhwtstamps, timestamp);
 
 	return ret;
 }
diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ptp.h b/drivers/net/ethernet/aquantia/atlantic/aq_ptp.h
index 28ccb7ca2df9..210b723f2207 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ptp.h
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ptp.h
@@ -67,7 +67,7 @@ int aq_ptp_hwtstamp_config_set(struct aq_ptp_s *aq_ptp,
 /* Return either ring is belong to PTP or not*/
 bool aq_ptp_ring(struct aq_nic_s *aq_nic, struct aq_ring_s *ring);
 
-u16 aq_ptp_extract_ts(struct aq_nic_s *aq_nic, struct sk_buff *skb, u8 *p,
+u16 aq_ptp_extract_ts(struct aq_nic_s *aq_nic, struct skb_shared_hwtstamps *shhwtstamps, u8 *p,
 		      unsigned int len);
 
 struct ptp_clock *aq_ptp_get_ptp_clock(struct aq_ptp_s *aq_ptp);
@@ -143,7 +143,7 @@ static inline bool aq_ptp_ring(struct aq_nic_s *aq_nic, struct aq_ring_s *ring)
 }
 
 static inline u16 aq_ptp_extract_ts(struct aq_nic_s *aq_nic,
-				    struct sk_buff *skb, u8 *p,
+				    struct skb_shared_hwtstamps *shhwtstamps, u8 *p,
 				    unsigned int len)
 {
 	return 0;
diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
index 4de22eed099a..694daeaf3e61 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -647,7 +647,7 @@ static int __aq_ring_rx_clean(struct aq_ring_s *self, struct napi_struct *napi,
 		}
 		if (is_ptp_ring)
 			buff->len -=
-				aq_ptp_extract_ts(self->aq_nic, skb,
+				aq_ptp_extract_ts(self->aq_nic, skb_hwtstamps(skb),
 						  aq_buf_vaddr(&buff->rxdata),
 						  buff->len);
 
@@ -742,6 +742,8 @@ static int __aq_ring_xdp_clean(struct aq_ring_s *rx_ring,
 		struct aq_ring_buff_s *buff = &rx_ring->buff_ring[rx_ring->sw_head];
 		bool is_ptp_ring = aq_ptp_ring(rx_ring->aq_nic, rx_ring);
 		struct aq_ring_buff_s *buff_ = NULL;
+		u16 ptp_hwtstamp_len = 0;
+		struct skb_shared_hwtstamps shhwtstamps;
 		struct sk_buff *skb = NULL;
 		unsigned int next_ = 0U;
 		struct xdp_buff xdp;
@@ -810,11 +812,12 @@ static int __aq_ring_xdp_clean(struct aq_ring_s *rx_ring,
 		hard_start = page_address(buff->rxdata.page) +
 			     buff->rxdata.pg_off - rx_ring->page_offset;
 
-		if (is_ptp_ring)
-			buff->len -=
-				aq_ptp_extract_ts(rx_ring->aq_nic, skb,
-						  aq_buf_vaddr(&buff->rxdata),
-						  buff->len);
+		if (is_ptp_ring) {
+			ptp_hwtstamp_len = aq_ptp_extract_ts(rx_ring->aq_nic, &shhwtstamps,
+							     aq_buf_vaddr(&buff->rxdata),
+							     buff->len);
+			buff->len -= ptp_hwtstamp_len;
+		}
 
 		xdp_init_buff(&xdp, frame_sz, &rx_ring->xdp_rxq);
 		xdp_prepare_buff(&xdp, hard_start, rx_ring->page_offset,
@@ -834,6 +837,9 @@ static int __aq_ring_xdp_clean(struct aq_ring_s *rx_ring,
 		if (IS_ERR(skb) || !skb)
 			continue;
 
+		if (ptp_hwtstamp_len > 0)
+			*skb_hwtstamps(skb) = shhwtstamps;
+
 		if (buff->is_vlan)
 			__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
 					       buff->vlan_rx_tag);
-- 
2.25.1