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019c892e46
Yi Lai reported RCU splat in reg_vif_xmit() below. [0]
When CONFIG_IP_MROUTE_MULTIPLE_TABLES=n, ipmr_fib_lookup()
uses rcu_dereference() without explicit rcu_read_lock().
Although rcu_read_lock_bh() is already held by the caller
__dev_queue_xmit(), lockdep requires explicit rcu_read_lock()
for rcu_dereference().
Let's move up rcu_read_lock() in reg_vif_xmit() to
cover ipmr_fib_lookup().
[0]:
WARNING: suspicious RCU usage
7.1.0-rc2-next-20260504-9d0d467c3572 #1 Not tainted
-----------------------------
net/ipv4/ipmr.c:329 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz.2.17/1779:
#0: ffffffff87896440 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#0: ffffffff87896440 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline]
#0: ffffffff87896440 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x239/0x4140 net/core/dev.c:4792
#1: ffff88801a199d18 (_xmit_PIMREG#2){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
#1: ffff88801a199d18 (_xmit_PIMREG#2){+...}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4795 [inline]
#1: ffff88801a199d18 (_xmit_PIMREG#2){+...}-{3:3}, at: __dev_queue_xmit+0x1d5d/0x4140 net/core/dev.c:4865
stack backtrace:
CPU: 1 UID: 0 PID: 1779 Comm: syz.2.17 Not tainted 7.1.0-rc2-next-20260504-9d0d467c3572 #1 PREEMPT(lazy)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x121/0x150 lib/dump_stack.c:120
dump_stack+0x19/0x20 lib/dump_stack.c:129
lockdep_rcu_suspicious+0x15b/0x1f0 kernel/locking/lockdep.c:6878
ipmr_fib_lookup net/ipv4/ipmr.c:329 [inline]
reg_vif_xmit+0x2ee/0x3c0 net/ipv4/ipmr.c:540
__netdev_start_xmit include/linux/netdevice.h:5382 [inline]
netdev_start_xmit include/linux/netdevice.h:5391 [inline]
xmit_one net/core/dev.c:3889 [inline]
dev_hard_start_xmit+0x170/0x700 net/core/dev.c:3905
__dev_queue_xmit+0x1df1/0x4140 net/core/dev.c:4871
dev_queue_xmit include/linux/netdevice.h:3423 [inline]
packet_xmit+0x252/0x370 net/packet/af_packet.c:276
packet_snd net/packet/af_packet.c:3082 [inline]
packet_sendmsg+0x39ad/0x5650 net/packet/af_packet.c:3114
sock_sendmsg_nosec net/socket.c:797 [inline]
__sock_sendmsg net/socket.c:812 [inline]
____sys_sendmsg+0xa21/0xba0 net/socket.c:2716
___sys_sendmsg+0x121/0x1c0 net/socket.c:2770
__sys_sendmsg+0x177/0x220 net/socket.c:2802
__do_sys_sendmsg net/socket.c:2807 [inline]
__se_sys_sendmsg net/socket.c:2805 [inline]
__x64_sys_sendmsg+0x80/0xc0 net/socket.c:2805
x64_sys_call+0x1d9c/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc1/0x1020 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f37e563ee5d
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 93 af 1b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe5caa7fa8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000005c5fa0 RCX: 00007f37e563ee5d
RDX: 0000000000000000 RSI: 00002000000012c0 RDI: 0000000000000004
RBP: 00000000005c5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00000000005c5fac R15: 00000000005c5fa0
</TASK>
Fixes:
|
||
|---|---|---|
| .. | ||
| 6lowpan | ||
| 9p | ||
| 802 | ||
| 8021q | ||
| appletalk | ||
| atm | ||
| batman-adv | ||
| bluetooth | ||
| bpf | ||
| bridge | ||
| can | ||
| ceph | ||
| core | ||
| dcb | ||
| devlink | ||
| dns_resolver | ||
| dsa | ||
| ethernet | ||
| ethtool | ||
| handshake | ||
| hsr | ||
| ieee802154 | ||
| ife | ||
| ipv4 | ||
| ipv6 | ||
| iucv | ||
| kcm | ||
| key | ||
| l2tp | ||
| l3mdev | ||
| lapb | ||
| llc | ||
| mac80211 | ||
| mac802154 | ||
| mctp | ||
| mpls | ||
| mptcp | ||
| ncsi | ||
| netfilter | ||
| netlabel | ||
| netlink | ||
| nfc | ||
| nsh | ||
| openvswitch | ||
| packet | ||
| phonet | ||
| psample | ||
| psp | ||
| qrtr | ||
| rds | ||
| rfkill | ||
| rxrpc | ||
| sched | ||
| sctp | ||
| shaper | ||
| smc | ||
| strparser | ||
| sunrpc | ||
| switchdev | ||
| tipc | ||
| tls | ||
| unix | ||
| vmw_vsock | ||
| wireless | ||
| x25 | ||
| xdp | ||
| xfrm | ||
| compat.c | ||
| devres.c | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| socket.c | ||
| sysctl_net.c | ||