CVE-2024-42071 ionic: use dev_consume_skb_any outside of napi
A bug in the Linux kernel's ionic network driver causes a kernel warning and potential instability when reconfiguring queues outside of NAPI context.
- 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-2024-42071?
CVE-2024-42071 is a high-severity denial of service vulnerability in Linux kernel, published on 29 Jul 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:
ionic: use dev_consume_skb_any outside of napi
If we're not in a NAPI softirq context, we need to be careful about how we call napi_consume_skb(), specifically we need to call it with budget==0 to signal to it that we're not in a safe context.
This was found while running some configuration stress testing of traffic and a change queue config loop running, and this curious note popped out:
[ 4371.402645] BUG: using smp_processor_id() in preemptible [00000000] code: ethtool/20545 [ 4371.402897] caller is napi_skb_cache_put+0x16/0x80 [ 4371.403120] CPU: 25 PID: 20545 Comm: ethtool Kdump: loaded Tainted: G OE 6.10.0-rc3-netnext+ #8 [ 4371.403302] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 01/23/2021 [ 4371.403460] Call Trace: [ 4371.403613] <TASK> [ 4371.403758] dump_stack_lvl+0x4f/0x70 [ 4371.403904] check_preemption_disabled+0xc1/0xe0 [ 4371.404051] napi_skb_cache_put+0x16/0x80 [ 4371.404199] ionic_tx_clean+0x18a/0x240 [ionic] [ 4371.404354] ionic_tx_cq_service+0xc4/0x200 [ionic] [ 4371.404505] ionic_tx_flush+0x15/0x70 [ionic] [ 4371.404653] ? ionic_lif_qcq_deinit.isra.23+0x5b/0x70 [ionic] [ 4371.404805] ionic_txrx_deinit+0x71/0x190 [ionic] [ 4371.404956] ionic_reconfigure_queues+0x5f5/0xff0 [ionic] [ 4371.405111] ionic_set_ringparam+0x2e8/0x3e0 [ionic] [ 4371.405265] ethnl_set_rings+0x1f1/0x300 [ 4371.405418] ethnl_default_set_doit+0xbb/0x160 [ 4371.405571] genl_family_rcv_msg_doit+0xff/0x130 [...]
I found that ionic_tx_clean() calls napi_consume_skb() which calls napi_skb_cache_put(), but before that last call is the note /* Zero budget indicate non-NAPI context called us, like netpoll */ and DEBUG_NET_WARN_ON_ONCE(!in_softirq());
Those are pretty big hints that we're doing it wrong. We can pass a context hint down through the calls to let ionic_tx_clean() know what we're doing so it can call napi_consume_skb() correctly.
Weakness: CWE-834
Which versions are affected by CVE-2024-42071?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-42071?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-42071 being exploited?
There is no known exploitation of CVE-2024-42071 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-47109, AZL-47192, BELL-CVE-2024-42071, DEBIAN-CVE-2024-42071, GHSA-rxwh-225r-76q6, UBUNTU-CVE-2024-42071.