CVE-2022-49330CVE-2022-49330

In the Linux kernel, the following vulnerability has been resolved: tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd syzbot got a new report [1] finally pointing to a very old bug, added in initial support for MTU probing. tcp_mtu_probe() has checks about starting an MTU probe if tcp_snd_cwnd(tp) >= 11. But nothing prevents tcp_snd_cwnd(tp) to be reduced later and before the MTU probe succeeds. This bug would lead to potential zero-divides. Debugging added in commit 40570375356c ("tcp: add accessors to read/set tp->snd_cwnd") has paid off :) While we are at it, address potential overflows in this code. [1] WARNING: CPU: 1 PID: 14132 at include/net/tcp.h:1219 tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712 Modules linked in: CPU: 1 PID: 14132 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-07857-gbabf0bb978e3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:tcp_snd_cwnd_set include/net/tcp.h:1219 [inline] RIP: