CVE-2021-47587 net: systemport: Add global locking for descriptor lifecycle
A race condition in the Linux kernel SYSTEMPORT driver allows concurrent transmit queues to corrupt network descriptors, potentially causing data corruption or 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-2021-47587?
CVE-2021-47587 is a critical vulnerability in Linux kernel, published on 19 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: systemport: Add global locking for descriptor lifecycle
The descriptor list is a shared resource across all of the transmit queues, and the locking mechanism used today only protects concurrency across a given transmit queue between the transmit and reclaiming. This creates an opportunity for the SYSTEMPORT hardware to work on corrupted descriptors if we have multiple producers at once which is the case when using multiple transmit queues.
This was particularly noticeable when using multiple flows/transmit queues and it showed up in interesting ways in that UDP packets would get a correct UDP header checksum being calculated over an incorrect packet length. Similarly TCP packets would get an equally correct checksum computed by the hardware over an incorrect packet length.
The SYSTEMPORT hardware maintains an internal descriptor list that it re-arranges when the driver produces a new descriptor anytime it writes to the WRITE_PORT_{HI,LO} registers, there is however some delay in the hardware to re-organize its descriptors and it is possible that concurrent TX queues eventually break this internal allocation scheme to the point where the length/status part of the descriptor gets used for an incorrect data buffer.
The fix is to impose a global serialization for all TX queues in the short section where we are writing to the WRITE_PORT_{HI,LO} registers which solves the corruption even with multiple concurrent TX queues being used.
Weakness: CWE-667
Which versions are affected by CVE-2021-47587?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47587?
Apply the vendor's patch.
Is CVE-2021-47587 being exploited?
There is no known exploitation of CVE-2021-47587 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47587, GHSA-gp83-h9gh-vrv6, UBUNTU-CVE-2021-47587.