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UBSan: misaligned memory loads in Objects/dictobject.c #127563

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encukou opened this issue Dec 3, 2024 · 5 comments
Closed

UBSan: misaligned memory loads in Objects/dictobject.c #127563

encukou opened this issue Dec 3, 2024 · 5 comments
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@picnixz
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3.12 bugs and security fixes 3.13 bugs and security fixes 3.14 new features, bugs and security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error

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@encukou
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encukou commented Dec 3, 2024 •
edited by bedevere-app bot
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Bug report

clang 18+'s undefined behavior sanitizer reports two cases of misaligned load:

Objects/unicodeobject.c:5088:24: runtime error: load of misaligned address 0x0000008b74be for type 'const size_t' (aka 'const unsigned long'), which requires 8 byte alignment
0x0000008b74be: note: pointer points here
 20 25 73 2e 5f 5f  72 65 70 72 5f 5f 00 72  61 77 20 73 74 72 65 61  6d 20 68 61 73 20 62 65  65 6e
             ^

and

Objects/dictobject.c:2015:40: runtime error: load of misaligned address 0x5f7d064233d1 for type 'PyDictUnicodeEntry *', which requires 8 byte alignment
0x5f7d064233d1: note: pointer points here
 00 00 00  ff ff ff ff ff ff ff ff  00 00 00 00 00 00 00 00  74 da 0f 06 7d 5f 00 00  df 01 00 00 14
              ^

Linked PRs
@encukou encukou added type-bug An unexpected behavior, bug, or error interpreter-core (Objects, Python, Grammar, and Parser dirs) labels Dec 3, 2024
@picnixz picnixz changed the title UBSan: misaligned memory loads UBSan: misaligned memory loads in Objects/unicodeobject.c and Objects/dictobject.c Dec 3, 2024
@picnixz picnixz changed the title UBSan: misaligned memory loads in Objects/unicodeobject.c and Objects/dictobject.c UBSan: misaligned memory loads in Objects/{dictobject,unicodeobject}.c Dec 3, 2024
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picnixz commented Dec 3, 2024

@encukou Are you planning to fix them now?

@encukou
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encukou commented Dec 3, 2024

Looking at my queue, I'll probably get to them next week. Feel free to take them now if you want.

@picnixz picnixz self-assigned this Dec 3, 2024
@picnixz picnixz added 3.12 bugs and security fixes 3.13 bugs and security fixes 3.14 new features, bugs and security fixes labels Dec 3, 2024
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picnixz commented Dec 3, 2024

I'll fix the issue in unicodeobject.c as part of #126024 instead and the dictobject.c as part of this issue.

@picnixz picnixz changed the title UBSan: misaligned memory loads in Objects/{dictobject,unicodeobject}.c UBSan: misaligned memory loads in Objects/dictobject.c Dec 3, 2024
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picnixz commented Dec 3, 2024

For the unicodeobject UBSan failure: #127566.

@bedevere-app bedevere-app bot mentioned this issue Dec 3, 2024
Merged
encukou pushed a commit that referenced this issue Dec 10, 2024
@picnixz
gh-127563: use dk_log2_index_bytes=3 in empty dicts (GH-127568)
9af96f4 
This fixes a UBSan failure (unaligned zero-size memcpy) in `dictobject.c`.
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Dec 10, 2024
@picnixz @miss-islington
pythongh-127563: use dk_log2_index_bytes=3 in empty dicts (pythonGH…
36f16aa 
…-127568)

This fixes a UBSan failure (unaligned zero-size memcpy) in `dictobject.c`.
(cherry picked from commit 9af96f4)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Dec 10, 2024
@picnixz @miss-islington
pythongh-127563: use dk_log2_index_bytes=3 in empty dicts (pythonGH…
f0ea126 
…-127568)

This fixes a UBSan failure (unaligned zero-size memcpy) in `dictobject.c`.
(cherry picked from commit 9af96f4)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
@bedevere-app bedevere-app bot mentioned this issue Dec 10, 2024
Merged
encukou pushed a commit that referenced this issue Dec 11, 2024
@miss-islington @picnixz
[3.13] gh-127563: use dk_log2_index_bytes=3 in empty dicts (GH-127568…
acf05aa 
…) (GH-127798)

This fixes a UBSan failure (unaligned zero-size memcpy) in `dictobject.c`.
(cherry picked from commit 9af96f4)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Dec 11, 2024
@picnixz @miss-islington
pythongh-127563: use dk_log2_index_bytes=3 in empty dicts (pythonGH…
5bf0bc3 
…-127568)

This fixes a UBSan failure (unaligned zero-size memcpy) in `dictobject.c`.
(cherry picked from commit 9af96f4)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
@bedevere-app bedevere-app bot mentioned this issue Dec 11, 2024
Merged
encukou pushed a commit that referenced this issue Dec 12, 2024
@miss-islington @picnixz
[3.12] gh-127563: use dk_log2_index_bytes=3 in empty dicts (GH-127568…
320a1dc 
…) (GH-127813)

This fixes a UBSan failure (unaligned zero-size memcpy) in `dictobject.c`.
(cherry picked from commit 9af96f4)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
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picnixz commented Dec 13, 2024

Closing since completed and backported.

@picnixz picnixz closed this as completed Dec 13, 2024
srinivasreddy pushed a commit to srinivasreddy/cpython that referenced this issue Jan 8, 2025
@picnixz @srinivasreddy
pythongh-127563: use dk_log2_index_bytes=3 in empty dicts (pythonGH…
43c8097 
…-127568)

This fixes a UBSan failure (unaligned zero-size memcpy) in `dictobject.c`.
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Labels
3.12 bugs and security fixes 3.13 bugs and security fixes 3.14 new features, bugs and security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error
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