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Fix heap-after-use between PROXYSQL INTERNAL SESSION and SHOW PROCESSLIST#5191

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renecannao merged 3 commits intov3.0from
v3.0-fix_proclist_use_after_free
Nov 5, 2025
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Fix heap-after-use between PROXYSQL INTERNAL SESSION and SHOW PROCESSLIST#5191
renecannao merged 3 commits intov3.0from
v3.0-fix_proclist_use_after_free

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@JavierJF
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@JavierJF JavierJF commented Oct 30, 2025

This PR fixes potential invalid memory accesses from SHOW PROCESSLIST. Missing query cleanup in 'PROXYSQL INTERNAL SESSION' could lead to invalid memory accesses during 'SHOW PROCESSLIST' sessions scan.

@JavierJF
Fix heap-after-use between 'PROXYSQL INTERNAL SESSION' and 'SHOW PROC…
4b28bb6 
…ESSLIST'

Missing query cleanup in 'PROXYSQL INTERNAL SESSION' could lead to
invalid memory accesses during 'SHOW PROCESSLIST' sessions scan.
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gemini-code-assist bot commented Oct 30, 2025

Summary of Changes

Hello @JavierJF, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a significant memory safety issue where SHOW PROCESSLIST could attempt to access memory that has already been freed by PROXYSQL INTERNAL SESSION operations. The core of the fix involves reordering memory deallocation to occur only after the session's request has been fully processed and logged. To ensure the stability and correctness of this fix, a new regression test has been added that specifically targets and reproduces the previously identified heap-after-use scenario.

Highlights

  • Heap-After-Use Fix: Addresses a critical heap-after-use vulnerability that could lead to invalid memory accesses when SHOW PROCESSLIST is executed concurrently with PROXYSQL INTERNAL SESSION commands.
  • Internal Session Cleanup: Ensures proper termination and cleanup of internal MySQL and PostgreSQL sessions by calling RequestEnd() before deallocating the associated packet memory, thus preventing memory corruption.
  • New Regression Test: Introduces a dedicated regression test case (reg_test_proclist_use_after_free-t.cpp) to simulate the race condition and validate the fix, safeguarding against future reintroductions of this bug.
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Code Review

This pull request correctly addresses a heap-use-after-free vulnerability by ensuring RequestEnd is called before the packet memory is freed. The logic is sound and the included comments clarify the change. The addition of a regression test is excellent for preventing this issue from recurring. I've found a minor area for improvement in the new test file to reduce code duplication.

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renecannao commented Oct 30, 2025

Can one of the admins verify this patch?

@JavierJF JavierJF force-pushed the v3.0-fix_proclist_use_after_free branch from 92a7fed to 6ff8501 Compare October 31, 2025 09:07
@JavierJF JavierJF requested a review from wazir-ahmed October 31, 2025 09:07
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renecannao commented Oct 31, 2025

Add to whitelist

@mirostauder
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mirostauder commented Nov 4, 2025

retest this please

@mirostauder
add tap test to groups.json
7051857 
Signed-off-by: Miro Stauder <miro@proxysql.com>
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sonarqubecloud bot commented Nov 4, 2025

Quality Gate Passed Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

@renecannao renecannao merged commit 4fa3bf6 into v3.0 Nov 5, 2025
144 of 154 checks passed
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@wazir-ahmed wazir-ahmed wazir-ahmed approved these changes

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@JavierJF @renecannao @mirostauder @wazir-ahmed