| Message ID | 20240807103943.1633950-1-dmantipov@yandex.ru (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [1/3] net: sched: fix use-after-free in taprio_change() | expand |
On Wed, 7 Aug 2024 13:39:41 +0300 Dmitry Antipov wrote: > In 'taprio_change()', 'admin' pointer may become dangling due to sched > switch / removal caused by 'advance_sched()', and critical section > protected by 'q->current_entry_lock' is too small to prevent from such > a scenario (which causes use-after-free detected by KASAN). Fix this > by prefer 'rcu_replace_pointer()' over 'rcu_assign_pointer()' to update > 'admin' immediately before an attempt to schedule freeing. > > Fixes: a3d43c0d56f1 ("taprio: Add support adding an admin schedule") > Reported-by: syzbot+b65e0af58423fc8a73aa@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa > Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru> No need to repost (yet?) but quick process note, please err on the side of incrementing patch versions, this should be a v2 even if only diff is that there are new patches. The version is for the _series_. https://lore.kernel.org/all/20240805135145.37604-1-dmantipov@yandex.ru/
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index cc2df9f8c14a..59fad74d5ff9 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -1963,7 +1963,8 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt, taprio_start_sched(sch, start, new_admin); - rcu_assign_pointer(q->admin_sched, new_admin); + admin = rcu_replace_pointer(q->admin_sched, new_admin, + lockdep_rtnl_is_held()); if (admin) call_rcu(&admin->rcu, taprio_free_sched_cb);
In 'taprio_change()', 'admin' pointer may become dangling due to sched switch / removal caused by 'advance_sched()', and critical section protected by 'q->current_entry_lock' is too small to prevent from such a scenario (which causes use-after-free detected by KASAN). Fix this by prefer 'rcu_replace_pointer()' over 'rcu_assign_pointer()' to update 'admin' immediately before an attempt to schedule freeing. Fixes: a3d43c0d56f1 ("taprio: Add support adding an admin schedule") Reported-by: syzbot+b65e0af58423fc8a73aa@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru> --- net/sched/sch_taprio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)