ixgbe: Fix NULL pointer dereference in ixgbe_xdp_setup

The ixgbe driver currently generates a NULL pointer dereference with
some machine (online cpus < 63). This is due to the fact that the
maximum value of num_xdp_queues is nr_cpu_ids. Code is in
"ixgbe_set_rss_queues"".

Here's how the problem repeats itself:
Some machine (online cpus < 63), And user set num_queues to 63 through
ethtool. Code is in the "ixgbe_set_channels",
	adapter->ring_feature[RING_F_FDIR].limit = count;

It becomes 63.

When user use xdp, "ixgbe_set_rss_queues" will set queues num.
	adapter->num_rx_queues = rss_i;
	adapter->num_tx_queues = rss_i;
	adapter->num_xdp_queues = ixgbe_xdp_queues(adapter);

And rss_i's value is from
	f = &adapter->ring_feature[RING_F_FDIR];
	rss_i = f->indices = f->limit;

So "num_rx_queues" > "num_xdp_queues", when run to "ixgbe_xdp_setup",
	for (i = 0; i < adapter->num_rx_queues; i++)
		if (adapter->xdp_ring[i]->xsk_umem)

It leads to panic.

Call trace:
[exception RIP: ixgbe_xdp+368]
RIP: ffffffffc02a76a0  RSP: ffff9fe16202f8d0  RFLAGS: 00010297
RAX: 0000000000000000  RBX: 0000000000000020  RCX: 0000000000000000
RDX: 0000000000000000  RSI: 000000000000001c  RDI: ffffffffa94ead90
RBP: ffff92f8f24c0c18   R8: 0000000000000000   R9: 0000000000000000
R10: ffff9fe16202f830  R11: 0000000000000000  R12: ffff92f8f24c0000
R13: ffff9fe16202fc01  R14: 000000000000000a  R15: ffffffffc02a7530
ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 7 [ffff9fe16202f8f0] dev_xdp_install at ffffffffa89fbbcc
 8 [ffff9fe16202f920] dev_change_xdp_fd at ffffffffa8a08808
 9 [ffff9fe16202f960] do_setlink at ffffffffa8a20235
10 [ffff9fe16202fa88] rtnl_setlink at ffffffffa8a20384
11 [ffff9fe16202fc78] rtnetlink_rcv_msg at ffffffffa8a1a8dd
12 [ffff9fe16202fcf0] netlink_rcv_skb at ffffffffa8a717eb
13 [ffff9fe16202fd40] netlink_unicast at ffffffffa8a70f88
14 [ffff9fe16202fd80] netlink_sendmsg at ffffffffa8a71319
15 [ffff9fe16202fdf0] sock_sendmsg at ffffffffa89df290
16 [ffff9fe16202fe08] __sys_sendto at ffffffffa89e19c8
17 [ffff9fe16202ff30] __x64_sys_sendto at ffffffffa89e1a64
18 [ffff9fe16202ff38] do_syscall_64 at ffffffffa84042b9
19 [ffff9fe16202ff50] entry_SYSCALL_64_after_hwframe at ffffffffa8c0008c

So I fix ixgbe_max_channels so that it will not allow a setting of queues
to be higher than the num_online_cpus(). And when run to ixgbe_xdp_setup,
take the smaller value of num_rx_queues and num_xdp_queues.

Fixes: b1a6a9e0c21b ("ixgbe: fix potential RX buffer starvation for AF_XDP")
Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
index fc26e4ddeb0dcf48922a1e91bbc5049874e6e5db..beda8e0ef7d421aa08c4521c3ac8cabe30539621 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
@@ -3208,7 +3208,7 @@ static unsigned int ixgbe_max_channels(struct ixgbe_adapter *adapter)
                max_combined = ixgbe_max_rss_indices(adapter);
        }
 
-       return max_combined;
+       return min_t(int, max_combined, num_online_cpus());
 }
 
 static void ixgbe_get_channels(struct net_device *dev,

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 24e06ba6f5e93de93fe167be3702421f68aadf66..13c4782b920a79f695553e5d3a11442ba74720f0 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -10112,6 +10112,7 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
        struct ixgbe_adapter *adapter = netdev_priv(dev);
        struct bpf_prog *old_prog;
        bool need_reset;
+       int num_queues;
 
        if (adapter->flags & IXGBE_FLAG_SRIOV_ENABLED)
                return -EINVAL;
@@ -10161,11 +10162,14 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
        /* Kick start the NAPI context if there is an AF_XDP socket open
         * on that queue id. This so that receiving will start.
         */
-       if (need_reset && prog)
-               for (i = 0; i < adapter->num_rx_queues; i++)
+       if (need_reset && prog) {
+               num_queues = min_t(int, adapter->num_rx_queues,
+                                  adapter->num_xdp_queues);
+               for (i = 0; i < num_queues; i++)
                        if (adapter->xdp_ring[i]->xsk_pool)
                                (void)ixgbe_xsk_wakeup(adapter->netdev, i,
                                                       XDP_WAKEUP_RX);
+       }
 
        return 0;
 }