CVE-2021-47399

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: ixgbe: corrige la desreferencia del puntero NULL en ixgbe_xdp_setup. El controlador ixgbe actualmente genera una desreferencia del puntero NULL con alguna máquina (cpus en línea <63). Esto se debe al hecho de que el valor máximo de num_xdp_queues es nr_cpu_ids. El código está en "ixgbe_set_rss_queues"". Así es como el problema se repite: alguna máquina (cpus en línea <63), y el usuario configuró num_queues en 63 a través de ethtool. El código está en "ixgbe_set_channels", adaptador->ring_feature[RING_F_FDIR].limit = count; se convierte en 63. Cuando el usuario usa xdp, "ixgbe_set_rss_queues" establecerá el número de colas adaptor->num_rx_queues = rss_i; = &adapter->ring_feature[RING_F_FDIR]; rss_i = f->indices = f->limit; Entonces "num_rx_queues" > "num_xdp_queues", cuando se ejecuta en "ixgbe_xdp_setup", para (i = 0; i < adaptor->num_rx_queues; i++) if (adapter->xdp_ring[i]->xsk_umem) Genera pánico: [excepción 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: ffff9fe1620 2f830 R11: 0000000000000000 R12: ffff92f8f24c0000 R13: ffff9fe16202fc01 R14: 000000000000000a R15: ffffffffc02a7530 ORIG_RAX: ffffffffffffffff CS: : 0018 7 [ffff9fe16202f8f0] dev_xdp_install en fffffffa89fbbcc 8 [ffff9fe16202f920] dev_change_xdp_fd en fffffffa8a08808 9 [ffff9fe16202f960] do_setlink en fffffffa8a20235 10 [ffff9fe16202fa88] rtnl_setlink en fffffffa8a20384 11 [ffff9fe16202fc78] rtnetlink_rcv_msg en ffffffffa8a1a8dd 12 [ffff9fe16202fcf0] netlink_rcv_skb en ffffffffa8a717eb 13 [ffff9fe16202fd40] netlink_unicast en fffffffa8a70f88 14 [ffff9fe162 02fd80] netlink_sendmsg en fffffffa8a71319 15 [ffff9fe16202fdf0] sock_sendmsg en ffffffffa89df290 16 [ffff9fe16202fe08] __sys_sendto en ffffffffa89e19c8 17 [ffff9fe16202ff30] __x64_sys_sendto en ffffffffa89e1a64 8 [ffff9fe16202ff38] do_syscall_64 en ffffffffa84042b9 19 [ffff9fe16202ff50] Entry_SYSCALL_64_after_hwframe en ffffffffa8c0008c Entonces arreglo ixgbe_max_channels para que no permita una configuración de colas ser mayor que num_online_cpus(). Y cuando ejecute ixgbe_xdp_setup, tome el valor más pequeño de num_rx_queues y num_xdp_queues.

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.