CVE-2024-56756 nvme-pci: fix freeing of the HMB descriptor table

What is CVE-2024-56756?

CVE-2024-56756 is a medium-severity use after free vulnerability in Linux kernel, published on 29 Dec 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:

nvme-pci: fix freeing of the HMB descriptor table

The HMB descriptor table is sized to the maximum number of descriptors that could be used for a given device, but __nvme_alloc_host_mem could break out of the loop earlier on memory allocation failure and end up using less descriptors than planned for, which leads to an incorrect size passed to dma_free_coherent.

In practice this was not showing up because the number of descriptors tends to be low and the dma coherent allocator always allocates and frees at least a page.

Which versions are affected by CVE-2024-56756?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-56756?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2024-56756 being exploited?

There is no known exploitation of CVE-2024-56756 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-54801, AZL-54830, BELL-CVE-2024-56756, DEBIAN-CVE-2024-56756, GHSA-2398-v7wm-x7gr, UBUNTU-CVE-2024-56756.