CVE-2024-53042

In the Linux kernel, the following vulnerability has been resolved:

ipv4: ip_tunnel: Fix suspicious RCU usage warning in ip_tunnel_init_flow()

There are code paths from which the function is called without holding

the RCU read lock, resulting in a suspicious RCU usage warning [1].

Fix by using l3mdev_master_upper_ifindex_by_index() which will acquire

the RCU read lock before calling

l3mdev_master_upper_ifindex_by_index_rcu().

[1]

WARNING: suspicious RCU usage

6.12.0-rc3-custom-gac8f72681cf2 #141 Not tainted

-----------------------------

net/core/dev.c:876 RCU-list traversed in non-reader section!!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1

1 lock held by ip/361:

#0: ffffffff86fc7cb0 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x377/0xf60

stack backtrace:

CPU: 3 UID: 0 PID: 361 Comm: ip Not tainted 6.12.0-rc3-custom-gac8f72681cf2 #141

Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011

Call Trace:

<TASK>

dump_stack_lvl+0xba/0x110

lockdep_rcu_suspicious.cold+0x4f/0xd6

dev_get_by_index_rcu+0x1d3/0x210

l3mdev_master_upper_ifindex_by_index_rcu+0x2b/0xf0

ip_tunnel_bind_dev+0x72f/0xa00

ip_tunnel_newlink+0x368/0x7a0

ipgre_newlink+0x14c/0x170

__rtnl_newlink+0x1173/0x19c0

rtnl_newlink+0x6c/0xa0

rtnetlink_rcv_msg+0x3cc/0xf60

netlink_rcv_skb+0x171/0x450

netlink_unicast+0x539/0x7f0

netlink_sendmsg+0x8c1/0xd80

____sys_sendmsg+0x8f9/0xc20

___sys_sendmsg+0x197/0x1e0

__sys_sendmsg+0x122/0x1f0

do_syscall_64+0xbb/0x1d0

entry_SYSCALL_64_after_hwframe+0x77/0x7f