We need to check __in6_dev_get() for possible NULL value, as suggested by Yiming Qian. Also add skb_dst_dev_rcu() instead of skb_dst_dev(), and two missing READ_ONCE(). Note that @dev can't be NULL. Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace") Reported-by: Yiming Qian Signed-off-by: Eric Dumazet Cc: Justin Iurman --- net/ipv6/ioam6.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/net/ipv6/ioam6.c b/net/ipv6/ioam6.c index 3978773bec424890cd18db78cf7cac9d3d652130..05a0b7d7e2aac35f634641fc4a791d1965dc85fd 100644 --- a/net/ipv6/ioam6.c +++ b/net/ipv6/ioam6.c @@ -710,7 +710,9 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, struct ioam6_schema *sc, unsigned int sclen, bool is_input) { - struct net_device *dev = skb_dst_dev(skb); + /* Note: skb_dst_dev_rcu() can't be NULL at this point. */ + struct net_device *dev = skb_dst_dev_rcu(skb); + struct inet6_dev *i_skb_dev, *idev; struct timespec64 ts; ktime_t tstamp; u64 raw64; @@ -721,13 +723,16 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, data = trace->data + trace->remlen * 4 - trace->nodelen * 4 - sclen * 4; + i_skb_dev = skb->dev ? __in6_dev_get(skb->dev) : NULL; + idev = __in6_dev_get(dev); + /* hop_lim and node_id */ if (trace->type.bit0) { byte = ipv6_hdr(skb)->hop_limit; if (is_input) byte--; - raw32 = dev_net(dev)->ipv6.sysctl.ioam6_id; + raw32 = READ_ONCE(dev_net(dev)->ipv6.sysctl.ioam6_id); *(__be32 *)data = cpu_to_be32((byte << 24) | raw32); data += sizeof(__be32); @@ -735,18 +740,18 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, /* ingress_if_id and egress_if_id */ if (trace->type.bit1) { - if (!skb->dev) + if (!i_skb_dev) raw16 = IOAM6_U16_UNAVAILABLE; else - raw16 = (__force u16)READ_ONCE(__in6_dev_get(skb->dev)->cnf.ioam6_id); + raw16 = (__force u16)READ_ONCE(i_skb_dev->cnf.ioam6_id); *(__be16 *)data = cpu_to_be16(raw16); data += sizeof(__be16); - if (dev->flags & IFF_LOOPBACK) + if ((dev->flags & IFF_LOOPBACK) || !idev) raw16 = IOAM6_U16_UNAVAILABLE; else - raw16 = (__force u16)READ_ONCE(__in6_dev_get(dev)->cnf.ioam6_id); + raw16 = (__force u16)READ_ONCE(idev->cnf.ioam6_id); *(__be16 *)data = cpu_to_be16(raw16); data += sizeof(__be16); @@ -822,7 +827,7 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, if (is_input) byte--; - raw64 = dev_net(dev)->ipv6.sysctl.ioam6_id_wide; + raw64 = READ_ONCE(dev_net(dev)->ipv6.sysctl.ioam6_id_wide); *(__be64 *)data = cpu_to_be64(((u64)byte << 56) | raw64); data += sizeof(__be64); @@ -830,18 +835,18 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, /* ingress_if_id and egress_if_id (wide) */ if (trace->type.bit9) { - if (!skb->dev) + if (!i_skb_dev) raw32 = IOAM6_U32_UNAVAILABLE; else - raw32 = READ_ONCE(__in6_dev_get(skb->dev)->cnf.ioam6_id_wide); + raw32 = READ_ONCE(i_skb_dev->cnf.ioam6_id_wide); *(__be32 *)data = cpu_to_be32(raw32); data += sizeof(__be32); - if (dev->flags & IFF_LOOPBACK) + if ((dev->flags & IFF_LOOPBACK) || !idev) raw32 = IOAM6_U32_UNAVAILABLE; else - raw32 = READ_ONCE(__in6_dev_get(dev)->cnf.ioam6_id_wide); + raw32 = READ_ONCE(idev->cnf.ioam6_id_wide); *(__be32 *)data = cpu_to_be32(raw32); data += sizeof(__be32); -- 2.53.0.1185.g05d4b7b318-goog