net/sched: act_api: avoid dereferencing ERR_PTR in tcf_idrinfo_destroy

net/sched: act_api: avoid dereferencing ERR_PTR in tcf_idrinfo_destroy

syzbot reported a crash in tc_act_in_hw() during netns teardown where
tcf_idrinfo_destroy() passed an ERR_PTR(-EBUSY) value as a tc_action
pointer, leading to an invalid dereference.

Guard against ERR_PTR entries when iterating the action IDR so teardown
does not call tc_act_in_hw() on an error pointer.

Fixes: 84a7d6797e6a ("net/sched: acp_api: no longer acquire RTNL in tc_action_net_exit()")
Link: https://syzkaller.appspot.com/bug?extid=8f1c492ffa4644ff3826
Reported-by: syzbot+8f1c492ffa4644ff3826@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8f1c492ffa4644ff3826
Signed-off-by: Shivani Gupta <shivani07g@gmail.com>
Link: https://patch.msgid.link/20260105005905.243423-1-shivani07g@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>