CVE-2023-52991

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

net: fix NULL pointer in skb_segment_list

Commit 3a1296a38d0c (net: Support GRO/GSO fraglist chaining.) introduced UDP listifyed GRO. The segmentation relies on frag_list being untouched when passing through the network stack. This assumption can be broken sometimes, where frag_list itself gets pulled into linear area, leaving frag_list being NULL. When this happens it can trigger following NULL pointer dereference, and panic the kernel. Reverse the test condition should fix it.

[19185.577801][ C1] BUG: kernel NULL pointer dereference, address: … [19185.663775][ C1] RIP: 0010:skb_segment_list+0x1cc/0x390 … [19185.834644][ C1] Call Trace: [19185.841730][ C1] [19185.848563][ C1] __udp_gso_segment+0x33e/0x510 [19185.857370][ C1] inet_gso_segment+0x15b/0x3e0 [19185.866059][ C1] skb_mac_gso_segment+0x97/0x110 [19185.874939][ C1] __skb_gso_segment+0xb2/0x160 [19185.883646][ C1] udp_queue_rcv_skb+0xc3/0x1d0 [19185.892319][ C1] udp_unicast_rcv_skb+0x75/0x90 [19185.900979][ C1] ip_protocol_deliver_rcu+0xd2/0x200 [19185.910003][ C1] ip_local_deliver_finish+0x44/0x60 [19185.918757][ C1] __netif_receive_skb_one_core+0x8b/0xa0 [19185.927834][ C1] process_backlog+0x88/0x130 [19185.935840][ C1] __napi_poll+0x27/0x150 [19185.943447][ C1] net_rx_action+0x27e/0x5f0 [19185.951331][ C1] ? mlx5_cq_tasklet_cb+0x70/0x160 [mlx5_core] [19185.960848][ C1] __do_softirq+0xbc/0x25d [19185.968607][ C1] irq_exit_rcu+0x83/0xb0 [19185.976247][ C1] common_interrupt+0x43/0xa0 [19185.984235][ C1] asm_common_interrupt+0x22/0x40 … [19186.094106][ C1]

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/046de74f9af92ae9ffce75fa22a1795223f4fb54
• https://git.kernel.org/stable/c/6446369fb9f083ce032448c5047da08e298b22e6
• https://git.kernel.org/stable/c/876e8ca8366735a604bac86ff7e2732fc9d85d2d
• https://git.kernel.org/stable/c/888dad6f3e85e3b2f8389bd6478f181efc72534d