Description

ashm-dev

opened on Oct 14, 2025

Issue body actions

Bug report

Bug Description:

A memory leak has been detected in the hmac module when running test_hmac. The issue appears to be specific to the Hacl_Streaming_HMAC implementation, as indicated by the stack traces from the AddressSanitizer (ASan) report. The leaks occur within functions responsible for HMAC digest computation (_Py_LibHacl_Hacl_Streaming_HMAC_digest, hmac_digest_compute_locked), suggesting that memory allocated during these operations is not being properly deallocated.

Steps to Reproduce:

1. Configure the build with the following flags to enable debugging and AddressSanitizer:

   CC=clang CXX=clang++ \
   ./configure \
   --disable-optimizations \
   --with-valgrind \
   --with-pydebug \
   --enable-pystats \
   --with-address-sanitizer

2. Build CPython:

   make -j$(nproc)

3. Run the hmac test suite:

   ./python -m test test_hmac

System Information:

• OS: Ubuntu 25.04 (Plucky Puffin)
• Kernel: Linux huawei 6.14.0-33-generic #33-Ubuntu SMP PREEMPT_DYNAMIC Wed Sep 17 23:22:02 UTC 2025 x86_64
• Clang Version: Ubuntu clang version 20.1.2 (0ubuntu1)

ASan Leak Report:

test.log

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-140120: Fix memory leak in HMAC digest #140124
• gh-140120: Refresh HACL* #140188
• [3.14] gh-140120: Refresh HACL* to fix an hmac memory leak (GH-140188) #140192

Activity

1. ashm-dev

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Oct 14, 2025
2. StanFromIreland

   added

   performancePerformance or resource usagePerformance or resource usage

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   on Oct 14, 2025
3. gpshead commented on Oct 14, 2025

   

   gpshead

   on Oct 14, 2025

   Member

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   patch from upstream hacl* needed - #140124 (comment)

   Reacted by Stan Ulbrych
4. protz commented on Oct 15, 2025

   

   protz

   on Oct 15, 2025

   Contributor

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   Thanks for the heads-up. Is there any more precise information as to where the issue occurs? Do we know which allocation is not freed?

   CC @R1kM
5. protz commented on Oct 15, 2025

   

   protz

   on Oct 15, 2025

   Contributor

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   Oh I see the patch is in https://github.com/python/cpython/pull/140124/files -- let me look into this.

   Reacted by Gregory P. Smith
6. protz commented on Oct 15, 2025

   

   protz

   on Oct 15, 2025

   Contributor

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   hacl-star/hacl-star#1064 has been merged so the next refresh of HACL* will have the fix. Thanks for reporting!

   Reacted by Shamil and Gregory P. Smith
7. gpshead

   self-assigned this

   on Oct 16, 2025
8. gpshead

   added a commit that references this issue on Oct 16, 2025

   gh-140120: Refresh HACL* to fix an hmac memory leak (GH-140188)

   3a81313
9. miss-islington

   added a commit that references this issue on Oct 16, 2025

   pythongh-140120: Refresh HACL* to fix an hmac memory leak (pythonGH-1…

   c1dc5eb
10. ashm-dev commented on Oct 16, 2025

    

    ashm-dev

    on Oct 16, 2025

    ContributorAuthor

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    I checked, there are no more leaks, thank you!

    Reacted by Sergey Miryanov

    Reacted by Gregory P. Smith
11. gpshead

    added a commit that references this issue on Oct 17, 2025

    [3.14] gh-140120: Refresh HACL* to fix an hmac memory leak (GH-140188) (

    32e60fa
12. gpshead commented on Oct 17, 2025

    

    gpshead

    on Oct 17, 2025

    Member

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    yay, thanks for finding this!
13. gpshead

    closed this as completedon Oct 17, 2025
14. gpshead

    added

    3.14bugs and security fixesbugs and security fixes

    on Oct 17, 2025
15. StanFromIreland

    added a commit that references this issue on Dec 6, 2025

    pythongh-140120: Refresh HACL* to fix an hmac memory leak (pythonGH-1…

    e417226

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