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] <TASK>

[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] </TASK>