CVE-2024-49980 vrf: revert "vrf: Remove unnecessary RCU-bh critical section"
A race condition in the Linux kernel VRF module can cause a deadlock, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-49980?
CVE-2024-49980 is a medium-severity vulnerability in Linux kernel, published on 21 Oct 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
vrf: revert "vrf: Remove unnecessary RCU-bh critical section"
This reverts commit 504fc6f4f7f681d2a03aa5f68aad549d90eab853.
dev_queue_xmit_nit is expected to be called with BH disabled. __dev_queue_xmit has the following:
/* Disable soft irqs for various locks below. Also * stops preemption for RCU. */ rcu_read_lock_bh();
VRF must follow this invariant. The referenced commit removed this protection. Which triggered a lockdep warning:
================================ WARNING: inconsistent lock state 6.11.0 #1 Tainted: G W -------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. btserver/134819 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff8882da30c118 (rlock-AF_PACKET){+.?.}-{2:2}, at: tpacket_rcv+0x863/0x3b30 {IN-SOFTIRQ-W} state was registered at: lock_acquire+0x19a/0x4f0 _raw_spin_lock+0x27/0x40 packet_rcv+0xa33/0x1320 __netif_receive_skb_core.constprop.0+0xcb0/0x3a90 __netif_receive_skb_list_core+0x2c9/0x890 netif_receive_skb_list_internal+0x610/0xcc0 [...]
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(rlock-AF_PACKET); <Interrupt> lock(rlock-AF_PACKET);
*** DEADLOCK ***
Call Trace: <TASK> dump_stack_lvl+0x73/0xa0 mark_lock+0x102e/0x16b0 __lock_acquire+0x9ae/0x6170 lock_acquire+0x19a/0x4f0 _raw_spin_lock+0x27/0x40 tpacket_rcv+0x863/0x3b30 dev_queue_xmit_nit+0x709/0xa40 vrf_finish_direct+0x26e/0x340 [vrf] vrf_l3_out+0x5f4/0xe80 [vrf] __ip_local_out+0x51e/0x7a0 [...]
Weakness: CWE-667
Which versions are affected by CVE-2024-49980?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-49980?
Apply the vendor's patch.
Is CVE-2024-49980 being exploited?
There is no known exploitation of CVE-2024-49980 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-49980, DEBIAN-CVE-2024-49980, GHSA-h72j-469c-c787, UBUNTU-CVE-2024-49980.