CVE-2023-53517

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tipc: do not update mtu if msg_max is too small in mtu negotiation<br /> <br /> When doing link mtu negotiation, a malicious peer may send Activate msg<br /> with a very small mtu, e.g. 4 in Shuang&amp;#39;s testing, without checking for<br /> the minimum mtu, l-&gt;mtu will be set to 4 in tipc_link_proto_rcv(), then<br /> n-&gt;links[bearer_id].mtu is set to 4294967228, which is a overflow of<br /> &amp;#39;4 - INT_H_SIZE - EMSG_OVERHEAD&amp;#39; in tipc_link_mss().<br /> <br /> With tipc_link.mtu = 4, tipc_link_xmit() kept printing the warning:<br /> <br /> tipc: Too large msg, purging xmit list 1 5 0 40 4!<br /> tipc: Too large msg, purging xmit list 1 15 0 60 4!<br /> <br /> And with tipc_link_entry.mtu 4294967228, a huge skb was allocated in<br /> named_distribute(), and when purging it in tipc_link_xmit(), a crash<br /> was even caused:<br /> <br /> general protection fault, probably for non-canonical address 0x2100001011000dd: 0000 [#1] PREEMPT SMP PTI<br /> CPU: 0 PID: 0 Comm: swapper/0 Kdump: loaded Not tainted 6.3.0.neta #19<br /> RIP: 0010:kfree_skb_list_reason+0x7e/0x1f0<br /> Call Trace:<br /> <br /> skb_release_data+0xf9/0x1d0<br /> kfree_skb_reason+0x40/0x100<br /> tipc_link_xmit+0x57a/0x740 [tipc]<br /> tipc_node_xmit+0x16c/0x5c0 [tipc]<br /> tipc_named_node_up+0x27f/0x2c0 [tipc]<br /> tipc_node_write_unlock+0x149/0x170 [tipc]<br /> tipc_rcv+0x608/0x740 [tipc]<br /> tipc_udp_recv+0xdc/0x1f0 [tipc]<br /> udp_queue_rcv_one_skb+0x33e/0x620<br /> udp_unicast_rcv_skb.isra.72+0x75/0x90<br /> __udp4_lib_rcv+0x56d/0xc20<br /> ip_protocol_deliver_rcu+0x100/0x2d0<br /> <br /> This patch fixes it by checking the new mtu against tipc_bearer_min_mtu(),<br /> and not updating mtu if it is too small.