# CVE-2021-47399: linux: In the Linux kernel, the following vulnerability has been resolved:  ixgbe: Fix NULL pointer dereference in ixgbe_xdp...

CVE-2021-47399 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47399, released May 21, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47399
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.14.12-1 | [DEBIAN-CVE-2021-47399](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47399.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.14.12-1 | [DEBIAN-CVE-2021-47399](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47399.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.14.12-1 | [DEBIAN-CVE-2021-47399](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47399.md) | May 21, 2024 |

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