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GeezerVison is showing github.com — GH-93964: Harden overflow checks before _PyBytes_Resize in compile.c by sweeneyde · Pull Request #94044 · python/cpython

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@sweeneyde

@sweeneyde sweeneyde commented Jun 21, 2022 •
edited by bedevere-bot
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#93964

The issue was found in 3.10, so it will need to be manually backported there.

  • Issue: Segfault compiling a very large source file #93964

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@sweeneyde
Harden overflow checks before _PyBytes_Resize in compile.c
72ab0f5
@sweeneyde
sweeneyde requested a review from markshannon as a code owner June 21, 2022 02:49
@bedevere-bot bedevere-bot added the awaiting core review label Jun 21, 2022
@blurb-it
📜🤖 Added by blurb_it.
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@sweeneyde
sweeneyde marked this pull request as draft June 21, 2022 03:43
@sweeneyde
Another test, more comments
e0054bf
@sweeneyde
sweeneyde marked this pull request as ready for review June 21, 2022 04:48
@sweeneyde sweeneyde added the needs backport to 3.11 only security fixes label Jun 21, 2022
@sweeneyde
remove unused variable
e05b51e
markshannon
markshannon reviewed Jun 28, 2022
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Comment thread Python/compile.c Outdated
Py_ssize_t b_len = PyBytes_GET_SIZE(*bytes);
if (unitsize * logical_length >= b_len - to_add * unitsize) {
// There's not enough room. Double it.
if (b_len > PY_SSIZE_T_MAX / 2) {

@markshannon markshannon Jun 28, 2022

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This has the same issue as the backport.
We want to be able to index all code object structures with an int, so you'll need INT_MAX instead of PY_SSIZE_T_MAX and it should be an overflow error, not a memory error.

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@sweeneyde sweeneyde Jul 26, 2022

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To clarify, we want a_bytecode to be able to have INT_MAX code units, not just INT_MAX bytes, right?

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@markshannon markshannon Mar 27, 2023

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We probably want the smaller amount to avoid risk of overflow. So the length in bytes should be less than INT_MAX.

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sweeneyde added 4 commits July 25, 2022 23:51
@sweeneyde
Merge remote-tracking branch 'upstream/main' into compile_overflows
cebc41b
@sweeneyde
simplify checks by using b_len/unitsize. use INT_MAX..
75a08cd
@sweeneyde
re-use b_len
7febdc8
@sweeneyde
remove misleading assertion
4a708eb
@sweeneyde sweeneyde mentioned this pull request Sep 2, 2022
Segfault compiling a very large source file #93964
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@arhadthedev

arhadthedev commented Apr 25, 2023

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Is the PR still relevant or some other PR superseded this one?

For merge conflict resolution: touched functions were moved to Python/assemble.c by gh-103277.

cc @iritkatriel
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@serhiy-storchaka serhiy-storchaka added needs backport to 3.12 only security fixes needs backport to 3.13 only security fixes and removed needs backport to 3.11 only security fixes labels May 9, 2024
@serhiy-storchaka serhiy-storchaka added the needs backport to 3.14 bugs and security fixes label May 8, 2025
@ZeroIntensity ZeroIntensity removed the needs backport to 3.12 only security fixes label May 29, 2025
@github-actions

github-actions Bot commented Apr 11, 2026

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This PR is stale because it has been open for 30 days with no activity.
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@github-actions github-actions Bot added the stale Stale PR or inactive for long period of time. label Apr 11, 2026
@serhiy-storchaka serhiy-storchaka added the needs backport to 3.15 bugs and security fixes label May 30, 2026
@github-actions github-actions Bot removed the stale Stale PR or inactive for long period of time. label Jun 5, 2026
@github-actions

github-actions Bot commented Sep 6, 2026

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This PR is stale because it has been open for 90 days with no activity.
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@github-actions github-actions Bot added the stale Stale PR or inactive for long period of time. label Sep 6, 2026
@ambv

ambv commented Oct 20, 2026

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Rebase review found this PR unportable: the assembler has since moved from compile.c to assemble.c and was rewritten around PyBytesWriter, so this 2022 hardening no longer applies; its issue gh-93964 is already closed. Closing to cull the number of open pull requests. If the hardening is still wanted, please open a new PR against the current assembler rather than reopening this one.
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@ambv ambv closed this Oct 20, 2026
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awaiting core review needs backport to 3.13 only security fixes needs backport to 3.14 bugs and security fixes needs backport to 3.15 bugs and security fixes stale Stale PR or inactive for long period of time.

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7 participants

@sweeneyde @arhadthedev @ambv @markshannon @serhiy-storchaka @bedevere-bot @ZeroIntensity
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