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

net/sched: taprio: extend minimum interval restriction to entire cycle too

It is possible for syzbot to side-step the restriction imposed by the
blamed commit in the Fixes: tag, because the taprio UAPI permits a
cycle-time different from (and potentially shorter than) the sum of
entry intervals.

We need one more restriction, which is that the cycle time itself must
be larger than N * ETH_ZLEN bit times, where N is the number of schedule
entries. This restriction needs to apply regardless of whether the cycle
time came from the user or was the implicit, auto-calculated value, so
we move the existing "cycle == 0" check outside the "if "(!new->cycle_time)"
branch. This way covers both conditions and scenarios.

Add a selftest which illustrates the issue triggered by syzbot.

kernel.org https://git.kernel.org/stable/c/91f249b01fe490fce11fbb4307952ca8cce78724 [No types assigned]

kernel.org https://git.kernel.org/stable/c/b939d1e04a90248b4cdf417b0969c270ceb992b2 [No types assigned]

kernel.org https://git.kernel.org/stable/c/fb66df20a7201e60f2b13d7f95d031b31a8831d3 [No types assigned]