CVE-2024-36962 net: ks8851: Queue RX packets in IRQ handler instead of disabling BHs

High 7.5 Published Updated

A race condition in the ks8851 network driver can cause a system hang when receiving packets, leading to denial of service.

Exploited in the wild
Not known
Login needed
Not needed
Attackable
Over the internet
Victim action needed
Not needed
Fix
Available

What is CVE-2024-36962?

CVE-2024-36962 is a high-severity vulnerability in Linux kernel, published on 3 Jun 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

net: ks8851: Queue RX packets in IRQ handler instead of disabling BHs

Currently the driver uses local_bh_disable()/local_bh_enable() in its IRQ handler to avoid triggering net_rx_action() softirq on exit from netif_rx(). The net_rx_action() could trigger this driver .start_xmit callback, which is protected by the same lock as the IRQ handler, so calling the .start_xmit from netif_rx() from the IRQ handler critical section protected by the lock could lead to an attempt to claim the already claimed lock, and a hang.

The local_bh_disable()/local_bh_enable() approach works only in case the IRQ handler is protected by a spinlock, but does not work if the IRQ handler is protected by mutex, i.e. this works for KS8851 with Parallel bus interface, but not for KS8851 with SPI bus interface.

Remove the BH manipulation and instead of calling netif_rx() inside the IRQ handler code protected by the lock, queue all the received SKBs in the IRQ handler into a queue first, and once the IRQ handler exits the critical section protected by the lock, dequeue all the queued SKBs and push them all into netif_rx(). At this point, it is safe to trigger the net_rx_action() softirq, since the netif_rx() call is outside of the lock that protects the IRQ handler.

Which versions are affected by CVE-2024-36962?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-36962?

Apply the vendor's patch.

Is CVE-2024-36962 being exploited?

There is no known exploitation of CVE-2024-36962 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2024-36962, DEBIAN-CVE-2024-36962, GHSA-j27x-m3vr-xwcf, UBUNTU-CVE-2024-36962.

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