fix: remove unsafe exec() in lockdown.c by orbisai0security · Pull Request #1712 · deepin-community/kernel

orbisai0security · 2026-05-14T07:51:09Z

Summary

Fix critical severity security issue in security/lockdown/lockdown.c.

Vulnerability

Field	Value
ID	V-001
Severity	CRITICAL
Scanner	multi_agent_ai
Rule	`V-001`
File	`security/lockdown/lockdown.c:103`

Description: The kernel lockdown security module uses sprintf() to build a string into a fixed-size stack buffer 'temp' at lines 103 and 105. The sprintf() function does not enforce any bound on the number of bytes written relative to the remaining buffer capacity. Each call accumulates bytes into 'offset' without checking whether the remaining buffer space is sufficient. If the 'label' string is longer than expected, the cumulative offset can exceed the buffer size, overwriting adjacent stack memory including saved registers and return addresses, enabling arbitrary code execution in kernel (ring 0) context.

Changes

security/lockdown/lockdown.c

Verification

Build passes
Scanner re-scan confirms fix
LLM code review passed

Automated security fix by OrbisAI Security

Summary by Sourcery

Bug Fixes:

Prevent potential stack buffer overflow in security/lockdown/lockdown.c by using length-limited string formatting when building lockdown reason labels.

Automated security fix generated by Orbis Security AI

sourcery-ai · 2026-05-14T07:51:16Z

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Replaces unsafe sprintf() calls with bounded snprintf() in the kernel lockdown module to eliminate a potential stack buffer overflow when formatting lockdown reason labels.

File-Level Changes

Change	Details	Files
Harden string formatting in lockdown_read() to prevent stack buffer overflow when building the lockdown reasons string.	Replace two sprintf() calls with snprintf() to enforce bounds on writes into the temp stack buffer. Pass remaining buffer size (sizeof(temp) - offset) to snprintf() so each write respects current offset and residual capacity. Preserve existing output format for the active and inactive lockdown reason labels while making the operation safe.	`security/lockdown/lockdown.c`

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deepin-ci-robot · 2026-05-14T07:51:21Z

Hi @orbisai0security. Thanks for your PR. 😃

deepin-ci-robot · 2026-05-14T07:51:26Z

Hi @orbisai0security. Thanks for your PR.

I'm waiting for a deepin-community member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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deepin-ci-robot · 2026-05-14T07:51:35Z

[APPROVALNOTIFIER] This PR is NOT APPROVED

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Once this PR has been reviewed and has the lgtm label, please assign avenger-285714 for approval. For more information see the Code Review Process.

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sourcery-ai

Hey - I've left some high level feedback:

When switching to snprintf, you should guard against offset growing beyond sizeof(temp) (to avoid size_t underflow in sizeof(temp) - offset) and early-return or stop appending once the buffer is full.
Consider using scnprintf (or at least checking the snprintf return value) so that offset is updated correctly in the presence of truncation rather than assuming the full string was written.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- When switching to snprintf, you should guard against offset growing beyond sizeof(temp) (to avoid size_t underflow in sizeof(temp) - offset) and early-return or stop appending once the buffer is full.
- Consider using scnprintf (or at least checking the snprintf return value) so that offset is updated correctly in the presence of truncation rather than assuming the full string was written.

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anupamme · 2026-05-14T08:01:34Z

Hey - I've left some high level feedback:

When switching to snprintf, you should guard against offset growing beyond sizeof(temp) (to avoid size_t underflow in sizeof(temp) - offset) and early-return or stop appending once the buffer is full.

Consider using scnprintf (or at least checking the snprintf return value) so that offset is updated correctly in the presence of truncation rather than assuming the full string was written.

Prompt for AI Agents
Please address the comments from this code review:

## Overall Comments
- When switching to snprintf, you should guard against offset growing beyond sizeof(temp) (to avoid size_t underflow in sizeof(temp) - offset) and early-return or stop appending once the buffer is full.
- Consider using scnprintf (or at least checking the snprintf return value) so that offset is updated correctly in the presence of truncation rather than assuming the full string was written.
Sourcery is free for open source - if you like our reviews please consider sharing them ✨

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@orbisai0security can you address code review comments?

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Pull request overview

Updates security/lockdown/lockdown.c to mitigate a reported stack buffer overflow risk when formatting lockdown reason labels into a fixed-size stack buffer.

Changes:

Replace sprintf() calls with snprintf() while building the temp buffer in lockdown_read().

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Avenger-285714 · 2026-05-14T11:59:28Z

 			if (kernel_locked_down == level)
-				offset += sprintf(temp+offset, "[%s] ", label);
+				offset += snprintf(temp+offset, sizeof(temp) - offset, "[%s] ", label);
 			else
-				offset += sprintf(temp+offset, "%s ", label);
+				offset += snprintf(temp+offset, sizeof(temp) - offset, "%s ", label);


Cc: @anupamme @orbisai0security

@orbisai0security can you address code review comments?

fix: V-001 security vulnerability

a72652d

Automated security fix generated by Orbis Security AI

deepin-ci-robot added the needs-ok-to-test label May 14, 2026

deepin-ci-robot requested review from Avenger-285714 and chenchongbiao May 14, 2026 07:51

sourcery-ai Bot reviewed May 14, 2026

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Avenger-285714 requested a review from Copilot May 14, 2026 08:02

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fix: remove unsafe exec() in lockdown.c#1712

fix: remove unsafe exec() in lockdown.c#1712
orbisai0security wants to merge 1 commit into
deepin-community:linux-6.6.yfrom
orbisai0security:fix-lockdown-sprintf-buffer-overflow

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