| Message ID | 20241018051339.418890-1-dmantipov@yandex.ru (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | f504465970aebb2467da548f7c1efbbf36d0f44b |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v7,1/2] net: sched: fix use-after-free in taprio_change() | expand |
Hello: This series was applied to netdev/net.git (main) by Paolo Abeni <pabeni@redhat.com>: On Fri, 18 Oct 2024 08:13:38 +0300 you 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. > > [...] Here is the summary with links: - [net,v7,1/2] net: sched: fix use-after-free in taprio_change() https://git.kernel.org/netdev/net/c/f504465970ae - [net,v7,2/2] net: sched: use RCU read-side critical section in taprio_dump() https://git.kernel.org/netdev/net/c/b22db8b8befe You are awesome, thank you!
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 8498d0606b24..9f4e004cdb8b 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -1965,7 +1965,8 @@ 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 Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru> --- v7: add (hopefully all required) process-related quirks v6: adjust to match recent changes 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(-)