| Message ID | 20241106131818.1240710-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v3,net-next] phonet: do not call synchronize_rcu() from phonet_route_del() | expand |
Wed, Nov 06, 2024 at 02:18:17PM CET, edumazet@google.com wrote: >Calling synchronize_rcu() while holding rcu_read_lock() is not >permitted [1] > >Move the synchronize_rcu() + dev_put() to route_doit(). > >Alternative would be to not use rcu_read_lock() in route_doit(). > >[1] >WARNING: suspicious RCU usage >6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0 Not tainted >----------------------------- >kernel/rcu/tree.c:4092 Illegal synchronize_rcu() in RCU read-side critical section! > >other info that might help us debug this: > >rcu_scheduler_active = 2, debug_locks = 1 >1 lock held by syz-executor427/5840: > #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] > #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] > #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: route_doit+0x3d6/0x640 net/phonet/pn_netlink.c:264 > >stack backtrace: >CPU: 1 UID: 0 PID: 5840 Comm: syz-executor427 Not tainted 6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0 >Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 >Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 > lockdep_rcu_suspicious+0x226/0x340 kernel/locking/lockdep.c:6821 > synchronize_rcu+0xea/0x360 kernel/rcu/tree.c:4089 > phonet_route_del+0xc6/0x140 net/phonet/pn_dev.c:409 > route_doit+0x514/0x640 net/phonet/pn_netlink.c:275 > rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6790 > netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2551 > netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline] > netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357 > netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901 > sock_sendmsg_nosec net/socket.c:729 [inline] > __sock_sendmsg+0x221/0x270 net/socket.c:744 > sock_write_iter+0x2d7/0x3f0 net/socket.c:1165 > new_sync_write fs/read_write.c:590 [inline] > vfs_write+0xaeb/0xd30 fs/read_write.c:683 > ksys_write+0x183/0x2b0 fs/read_write.c:736 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > >Fixes: 17a1ac0018ae ("phonet: Don't hold RTNL for route_doit().") >Reported-by: syzbot <syzkaller@googlegroups.com> >Signed-off-by: Eric Dumazet <edumazet@google.com> >Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c index 19234d664c4fb537eba0267266efbb226cf103c3..5c36bae37b8fa85d2e97bf11d099c6c8599dcc5f 100644 --- a/net/phonet/pn_dev.c +++ b/net/phonet/pn_dev.c @@ -406,8 +406,9 @@ int phonet_route_del(struct net_device *dev, u8 daddr) if (!dev) return -ENOENT; - synchronize_rcu(); - dev_put(dev); + + /* Note : our caller must call synchronize_rcu() and dev_put(dev) */ + return 0; } diff --git a/net/phonet/pn_netlink.c b/net/phonet/pn_netlink.c index ca1f04e4a2d9eb3b2a6d6cc5b299aee28d569b08..b9043c92dc246f8c5c313b262eb3ec4afad47ecb 100644 --- a/net/phonet/pn_netlink.c +++ b/net/phonet/pn_netlink.c @@ -233,6 +233,7 @@ static int route_doit(struct sk_buff *skb, struct nlmsghdr *nlh, { struct net *net = sock_net(skb->sk); struct nlattr *tb[RTA_MAX+1]; + bool sync_needed = false; struct net_device *dev; struct rtmsg *rtm; u32 ifindex; @@ -269,13 +270,20 @@ static int route_doit(struct sk_buff *skb, struct nlmsghdr *nlh, return -ENODEV; } - if (nlh->nlmsg_type == RTM_NEWROUTE) + if (nlh->nlmsg_type == RTM_NEWROUTE) { err = phonet_route_add(dev, dst); - else + } else { err = phonet_route_del(dev, dst); + if (!err) + sync_needed = true; + } rcu_read_unlock(); + if (sync_needed) { + synchronize_rcu(); + dev_put(dev); + } if (!err) rtm_phonet_notify(net, nlh->nlmsg_type, ifindex, dst);
Calling synchronize_rcu() while holding rcu_read_lock() is not permitted [1] Move the synchronize_rcu() + dev_put() to route_doit(). Alternative would be to not use rcu_read_lock() in route_doit(). [1] WARNING: suspicious RCU usage 6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0 Not tainted ----------------------------- kernel/rcu/tree.c:4092 Illegal synchronize_rcu() in RCU read-side critical section! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by syz-executor427/5840: #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: route_doit+0x3d6/0x640 net/phonet/pn_netlink.c:264 stack backtrace: CPU: 1 UID: 0 PID: 5840 Comm: syz-executor427 Not tainted 6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 lockdep_rcu_suspicious+0x226/0x340 kernel/locking/lockdep.c:6821 synchronize_rcu+0xea/0x360 kernel/rcu/tree.c:4089 phonet_route_del+0xc6/0x140 net/phonet/pn_dev.c:409 route_doit+0x514/0x640 net/phonet/pn_netlink.c:275 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6790 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2551 netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline] netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357 netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901 sock_sendmsg_nosec net/socket.c:729 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:744 sock_write_iter+0x2d7/0x3f0 net/socket.c:1165 new_sync_write fs/read_write.c:590 [inline] vfs_write+0xaeb/0xd30 fs/read_write.c:683 ksys_write+0x183/0x2b0 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 17a1ac0018ae ("phonet: Don't hold RTNL for route_doit().") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Cc: Remi Denis-Courmont <courmisch@gmail.com> --- v3: proper tree (net-next) v2: also move dev_put() to keep it after synchronize_rcu() net/phonet/pn_dev.c | 5 +++-- net/phonet/pn_netlink.c | 12 ++++++++++-- 2 files changed, 13 insertions(+), 4 deletions(-)