| Message ID | 20240904120842.3426084-1-dmantipov@yandex.ru (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v5,1/2] net: sched: fix use-after-free in taprio_change() | expand |
Dmitry Antipov <dmantipov@yandex.ru> writes: > 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> > --- > v5: unchanged since v4 but resend due to series change > v4: adjust subject to target net tree > v3: unchanged since v2 > v2: unchanged since v1 > --- Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> Cheers,
Just a friendly reminder. Note the net-next counterpart of this series (https://lore.kernel.org/netdev/87wmjqnufp.fsf@intel.com/T/#t) is already merged (both to net and net-next). Dmitry On 9/5/24 3:43 PM, Vinicius Costa Gomes wrote: > Dmitry Antipov <dmantipov@yandex.ru> writes: > >> 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> >> --- >> v5: unchanged since v4 but resend due to series change >> v4: adjust subject to target net tree >> v3: unchanged since v2 >> v2: unchanged since v1 >> --- > > Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> > > > Cheers,
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> --- v5: unchanged since v4 but resend due to series change v4: adjust subject to target net tree v3: unchanged since v2 v2: unchanged since v1 --- net/sched/sch_taprio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)