[PATCH 5.10 55/93] ixgbe: Fix NULL pointer dereference in ixgbe_xdp_setup

Greg Kroah-Hartman
2021-10-04T13:24:59Z

From: Feng Zhou <zhoufeng.zf@bytedance.com>

[ Upstream commit 513e605d7a9ce136886cb42ebb2c40e9a6eb6333 ]

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: 4a9b32f30f80 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c | 2 +-
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 8 ++++++--
2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
index a280aa34ca1d..55983904b6df 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
@@ -3216,7 +3216,7 @@ 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 37439b76fcb5..ffe322136c58 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -10123,6 +10123,7 @@ 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;
@@ -10172,11 +10173,14 @@ 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;
}
--
2.33.0