Eric Dumazet 56440d7ec2 genetlink: hold RCU in genlmsg_mcast() ... 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] <TASK> [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: 33f72e6f0c ("l2tp : multicast notification to the registered listeners") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: James Chapman <jchapman@katalix.com> Cc: Tom Parkin <tparkin@katalix.com> Cc: Johannes Berg <johannes.berg@intel.com> Link: https://patch.msgid.link/20241011171217.3166614-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>		2024-10-15 17:52:58 -07:00
..
certs
tests
.gitignore
ap.c
chan.c
core.c
core.h	wifi: cfg80211: skip indicating signal for per-STA profile BSSs	2024-09-06 12:56:33 +02:00
debugfs.c
debugfs.h
ethtool.c
ibss.c	wifi: cfg80211: move DFS related members to links[] in wireless_dev	2024-09-06 13:01:05 +02:00
Kconfig
lib80211.c
lib80211_crypt_ccmp.c
lib80211_crypt_tkip.c
lib80211_crypt_wep.c
Makefile
mesh.c	wifi: cfg80211: move DFS related members to links[] in wireless_dev	2024-09-06 13:01:05 +02:00
mlme.c	wifi: cfg80211/mac80211: use proper link ID for DFS	2024-09-06 13:01:05 +02:00
nl80211.c	genetlink: hold RCU in genlmsg_mcast()	2024-10-15 17:52:58 -07:00
nl80211.h
ocb.c
of.c
pmsr.c
radiotap.c	move asm/unaligned.h to linux/unaligned.h	2024-10-02 17:23:23 -04:00
rdev-ops.h	wifi: cfg80211: handle DFS per link	2024-09-06 13:01:05 +02:00
reg.c	wifi: cfg80211: handle DFS per link	2024-09-06 13:01:05 +02:00
reg.h
scan.c	wifi: cfg80211: avoid overriding direct/MBSSID BSS with per-STA profile BSS	2024-09-06 12:56:33 +02:00
sme.c	wifi: cfg80211: fix two more possible UBSAN-detected off-by-one errors	2024-09-09 11:43:21 +02:00
sysfs.c
sysfs.h
trace.c
trace.h	wifi: cfg80211: handle DFS per link	2024-09-06 13:01:05 +02:00
util.c
wext-compat.c
wext-compat.h
wext-core.c
wext-priv.c
wext-proc.c
wext-sme.c
wext-spy.c