CVE-2026-93264 RDMA/efa: Fix PBL chunk length computation
A logic error in the EFA RDMA driver causes incorrect chunk length calculations, leading to memory registration failures and potential 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-2026-93264?
CVE-2026-93264 is a vulnerability in Linux, published on 24 Sep 2026. 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:
RDMA/efa: Fix PBL chunk length computation
On register MR, when creating the PBL, if it's an indirect PBL we create a chunk list to hold the PBL pages pointers. Each chunk is 4KB in size and can hold 510 addresses (EFA_PTRS_PER_CHUNK) and has a 12-byte control buffer at the end of it holding the next chunk's pointer and its length.
If the PBL number of pages is a multiple of EFA_PTRS_PER_CHUNK, the calculated last chunk length is wrongly computed as 0, even though that chunk is fully populated with 510 real page pointers. This wrong length is used both to DMA map the chunk and is propagated to the device, causing the device to see the chunk as empty and reject the memory registration.
Fix the calculation so it will be performed only if the number of pages isn't a multiple of EFA_PTRS_PER_CHUNK, if it is, its already handled in the above loop correctly. Also prevent out-of-bounds reach in the chunks array in such scenario.
Which versions are affected by CVE-2026-93264?
How do I fix CVE-2026-93264?
Apply the vendor's patch.
Is CVE-2026-93264 being exploited?
There is no known exploitation of CVE-2026-93264 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-93264, DEBIAN-CVE-2026-93264, GHSA-w4pg-rf77-8rgx, UBUNTU-CVE-2026-93264.