In the Linux kernel, the following vulnerability has been resolved: tcp: add accessors to read/set tp->sndcwnd We had various bugs over the years with code breaking the assumption that tp->sndcwnd is greater than zero. Lately, syzbot reported the WARNONONCE(!tp->priorcwnd) added in commit 8b8a321ff72c ("tcp: fix zero cwnd in tcpcwndreduction") can trigger, and without a repro we would have to spend considerable time finding the bug. Instead of complaining too late, we want to catch where and when tp->sndcwnd is set to an illegal value.