kernel/linux.git/net/l2tp, branch v6.12.80

l2tp: avoid one data-race in l2tp_tunnel_del_work()

2026-01-30T09:28:39+00:00

[ Upstream commit 7a29f6bf60f2590fe5e9c4decb451e19afad2bcf ] We should read sk->sk_socket only when dealing with kernel sockets. syzbot reported the following data-race: BUG: KCSAN: data-race in l2tp_tunnel_del_work / sk_common_release write to 0xffff88811c182b20 of 8 bytes by task 5365 on cpu 0: sk_set_socket include/net/sock.h:2092 [inline] sock_orphan include/net/sock.h:2118 [inline] sk_common_release+0xae/0x230 net/core/sock.c:4003 udp_lib_close+0x15/0x20 include/net/udp.h:325 inet_release+0xce/0xf0 net/ipv4/af_inet.c:437 __sock_release net/socket.c:662 [inline] sock_close+0x6b/0x150 net/socket.c:1455 __fput+0x29b/0x650 fs/file_table.c:468 ____fput+0x1c/0x30 fs/file_table.c:496 task_work_run+0x131/0x1a0 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:44 [inline] exit_to_user_mode_loop+0x1fe/0x740 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x1e1/0x2b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff88811c182b20 of 8 bytes by task 827 on cpu 1: l2tp_tunnel_del_work+0x2f/0x1a0 net/l2tp/l2tp_core.c:1418 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340 worker_thread+0x582/0x770 kernel/workqueue.c:3421 kthread+0x489/0x510 kernel/kthread.c:463 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 value changed: 0xffff88811b818000 -> 0x0000000000000000 Fixes: d00fa9adc528 ("l2tp: fix races with tunnel socket close") Reported-by: syzbot+7312e82745f7fa2526db@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6968b029.050a0220.58bed.0016.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: James Chapman Reviewed-by: Guillaume Nault Link: https://patch.msgid.link/20260115092139.3066180-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

l2tp: Fix memleak in l2tp_udp_encap_recv().

2026-01-30T09:28:38+00:00

[ Upstream commit 4d10edfd1475b69dbd4c47f34b61a3772ece83ca ] syzbot reported memleak of struct l2tp_session, l2tp_tunnel, sock, etc. [0] The cited commit moved down the validation of the protocol version in l2tp_udp_encap_recv(). The new place requires an extra error handling to avoid the memleak. Let's call l2tp_session_put() there. [0]: BUG: memory leak unreferenced object 0xffff88810a290200 (size 512): comm "syz.0.17", pid 6086, jiffies 4294944299 hex dump (first 32 bytes): 7d eb 04 0c 00 00 00 00 01 00 00 00 00 00 00 00 }............... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc babb6a4f): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4958 [inline] slab_alloc_node mm/slub.c:5263 [inline] __do_kmalloc_node mm/slub.c:5656 [inline] __kmalloc_noprof+0x3e0/0x660 mm/slub.c:5669 kmalloc_noprof include/linux/slab.h:961 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] l2tp_session_create+0x3a/0x3b0 net/l2tp/l2tp_core.c:1778 pppol2tp_connect+0x48b/0x920 net/l2tp/l2tp_ppp.c:755 __sys_connect_file+0x7a/0xb0 net/socket.c:2089 __sys_connect+0xde/0x110 net/socket.c:2108 __do_sys_connect net/socket.c:2114 [inline] __se_sys_connect net/socket.c:2111 [inline] __x64_sys_connect+0x1c/0x30 net/socket.c:2111 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 364798056f518 ("l2tp: Support different protocol versions with same IP/port quadruple") Reported-by: syzbot+2c42ea4485b29beb0643@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/696693f2.a70a0220.245e30.0001.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Guillaume Nault Link: https://patch.msgid.link/20260113185446.2533333-1-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

l2tp: do not use sock_hold() in pppol2tp_session_get_sock()

2025-09-04T13:31:51+00:00

[ Upstream commit 9b8c88f875c04d4cb9111bd5dd9291c7e9691bf5 ] pppol2tp_session_get_sock() is using RCU, it must be ready for sk_refcnt being zero. Commit ee40fb2e1eb5 ("l2tp: protect sock pointer of struct pppol2tp_session with RCU") was correct because it had a call_rcu(..., pppol2tp_put_sk) which was later removed in blamed commit. pppol2tp_recv() can use pppol2tp_session_get_sock() as well. Fixes: c5cbaef992d6 ("l2tp: refactor ppp socket/session relationship") Signed-off-by: Eric Dumazet Cc: James Chapman Reviewed-by: Guillaume Nault Link: https://patch.msgid.link/20250826134435.1683435-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: replace ipcm6_init calls with ipcm6_init_sk

2025-06-27T10:11:41+00:00

commit 096208592b09c2f5fc0c1a174694efa41c04209d upstream. This initializes tclass and dontfrag before cmsg parsing, removing the need for explicit checks against -1 in each caller. Leave hlimit set to -1, because its full initialization (in ip6_sk_dst_hoplimit) requires more state (dst, flowi6, ..). This also prepares for calling sockcm_init in a follow-on patch. Signed-off-by: Willem de Bruijn Reviewed-by: David Ahern Link: https://patch.msgid.link/20250214222720.3205500-7-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/l2tp: fix warning in l2tp_exit_net found by syzbot

2024-12-05T13:02:31+00:00

[ Upstream commit 5d066766c5f1252f98ff859265bcd1a5b52ac46c ] In l2tp's net exit handler, we check that an IDR is empty before destroying it: WARN_ON_ONCE(!idr_is_empty(&pn->l2tp_tunnel_idr)); idr_destroy(&pn->l2tp_tunnel_idr); By forcing memory allocation failures in idr_alloc_32, syzbot is able to provoke a condition where idr_is_empty returns false despite there being no items in the IDR. This turns out to be because the radix tree of the IDR contains only internal radix-tree nodes and it is this that causes idr_is_empty to return false. The internal nodes are cleaned by idr_destroy. Use idr_for_each to check that the IDR is empty instead of idr_is_empty to avoid the problem. Reported-by: syzbot+332fe1e67018625f63c9@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=332fe1e67018625f63c9 Fixes: 73d33bd063c4 ("l2tp: avoid using drain_workqueue in l2tp_pre_exit_net") Signed-off-by: James Chapman Link: https://patch.msgid.link/20241118140411.1582555-1-jchapman@katalix.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

genetlink: hold RCU in genlmsg_mcast()

2024-10-16T00:52:58+00:00

While running net selftests with CONFIG_PROVE_RCU_LIST=y I saw one lockdep splat [1]. genlmsg_mcast() uses for_each_net_rcu(), and must therefore hold RCU. Instead of letting all callers guard genlmsg_multicast_allns() with a rcu_read_lock()/rcu_read_unlock() pair, do it in genlmsg_mcast(). This also means the @flags parameter is useless, we need to always use GFP_ATOMIC. [1] [10882.424136] ============================= [10882.424166] WARNING: suspicious RCU usage [10882.424309] 6.12.0-rc2-virtme #1156 Not tainted [10882.424400] ----------------------------- [10882.424423] net/netlink/genetlink.c:1940 RCU-list traversed in non-reader section!! [10882.424469] other info that might help us debug this: [10882.424500] rcu_scheduler_active = 2, debug_locks = 1 [10882.424744] 2 locks held by ip/15677: [10882.424791] #0: ffffffffb6b491b0 (cb_lock){++++}-{3:3}, at: genl_rcv (net/netlink/genetlink.c:1219) [10882.426334] #1: ffffffffb6b49248 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg (net/netlink/genetlink.c:61 net/netlink/genetlink.c:57 net/netlink/genetlink.c:1209) [10882.426465] stack backtrace: [10882.426805] CPU: 14 UID: 0 PID: 15677 Comm: ip Not tainted 6.12.0-rc2-virtme #1156 [10882.426919] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [10882.427046] Call Trace: [10882.427131] [10882.427244] dump_stack_lvl (lib/dump_stack.c:123) [10882.427335] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822) [10882.427387] genlmsg_multicast_allns (net/netlink/genetlink.c:1940 (discriminator 7) net/netlink/genetlink.c:1977 (discriminator 7)) [10882.427436] l2tp_tunnel_notify.constprop.0 (net/l2tp/l2tp_netlink.c:119) l2tp_netlink [10882.427683] l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:253) l2tp_netlink [10882.427748] genl_family_rcv_msg_doit (net/netlink/genetlink.c:1115) [10882.427834] genl_rcv_msg (net/netlink/genetlink.c:1195 net/netlink/genetlink.c:1210) [10882.427877] ? __pfx_l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:186) l2tp_netlink [10882.427927] ? __pfx_genl_rcv_msg (net/netlink/genetlink.c:1201) [10882.427959] netlink_rcv_skb (net/netlink/af_netlink.c:2551) [10882.428069] genl_rcv (net/netlink/genetlink.c:1220) [10882.428095] netlink_unicast (net/netlink/af_netlink.c:1332 net/netlink/af_netlink.c:1357) [10882.428140] netlink_sendmsg (net/netlink/af_netlink.c:1901) [10882.428210] ____sys_sendmsg (net/socket.c:729 (discriminator 1) net/socket.c:744 (discriminator 1) net/socket.c:2607 (discriminator 1)) Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners") Signed-off-by: Eric Dumazet Cc: James Chapman Cc: Tom Parkin Cc: Johannes Berg Link: https://patch.msgid.link/20241011171217.3166614-1-edumazet@google.com Signed-off-by: Jakub Kicinski

l2tp: remove unneeded null check in l2tp_v2_session_get_next

2024-09-04T23:39:32+00:00

Commit aa92c1cec92b ("l2tp: add tunnel/session get_next helpers") uses idr_get_next APIs to iterate over l2tp session IDR lists. Sessions in l2tp_v2_session_idr always have a non-null session->tunnel pointer since l2tp_session_register sets it before inserting the session into the IDR. Therefore the null check on session->tunnel in l2tp_v2_session_get_next is redundant and can be removed. Removing the check avoids a warning from lkp. Reported-by: kernel test robot Closes: https://lore.kernel.org/r/202408111407.HtON8jqa-lkp@intel.com/ CC: Dan Carpenter Signed-off-by: James Chapman Acked-by: Tom Parkin Reviewed-by: Simon Horman Link: https://patch.msgid.link/20240903113547.1261048-1-jchapman@katalix.com Signed-off-by: Jakub Kicinski

netdev_features: convert NETIF_F_LLTX to dev->lltx

2024-09-03T09:36:43+00:00

NETIF_F_LLTX can't be changed via Ethtool and is not a feature, rather an attribute, very similar to IFF_NO_QUEUE (and hot). Free one netdev_features_t bit and make it a "hot" private flag. Signed-off-by: Alexander Lobakin Signed-off-by: Paolo Abeni

l2tp: avoid using drain_workqueue in l2tp_pre_exit_net

2024-08-27T20:37:22+00:00

Recent commit fc7ec7f554d7 ("l2tp: delete sessions using work queue") incorrectly uses drain_workqueue. The use of drain_workqueue in l2tp_pre_exit_net is flawed because the workqueue is shared by all nets and it is therefore possible for new work items to be queued for other nets while drain_workqueue runs. Instead of using drain_workqueue, use __flush_workqueue twice. The first one will run all tunnel delete work items and any work already queued. When tunnel delete work items are run, they may queue new session delete work items, which the second __flush_workqueue will run. In l2tp_exit_net, warn if any of the net's idr lists are not empty. Fixes: fc7ec7f554d7 ("l2tp: delete sessions using work queue") Signed-off-by: James Chapman Link: https://patch.msgid.link/20240823142257.692667-1-jchapman@katalix.com Signed-off-by: Jakub Kicinski

l2tp: avoid overriding sk->sk_user_data

2024-08-26T16:55:40+00:00

Although commit 4a4cd70369f1 ("l2tp: don't set sk_user_data in tunnel socket") removed sk->sk_user_data usage, setup_udp_tunnel_sock() still touches sk->sk_user_data, this conflicts with sockmap which also leverages sk->sk_user_data to save psock. Restore this sk->sk_user_data check to avoid such conflicts. Fixes: 4a4cd70369f1 ("l2tp: don't set sk_user_data in tunnel socket") Reported-by: syzbot+8dbe3133b840c470da0e@syzkaller.appspotmail.com Cc: Tom Parkin Signed-off-by: Cong Wang Tested-by: James Chapman Reviewed-by: James Chapman Link: https://patch.msgid.link/20240822182544.378169-1-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski