gh-128840: Limit the number of parts in IPv6 address parsing by sethmlarson · Pull Request #128841 · python/cpython · GitHub

Issue: IPv6 address parsing doesn't limit buffer size #128840

Looks great, thank you @sethmlarson!

@sethmlarson How does this fix prevents a potential denial-of-service ?

This prevents excessive memory consumption and potential
denial-of-service when parsing a large IPv6 address.

In the case when we end up with ip_str with extra :, all this fix causes is that the list created in the split call is shorter (Reduced memory usage, and Less CPU instruction due to prevention of additional append calls to the allocated list).
Even if this fix is not there, program will just consume a bit more memory and a bit more cpu (as @serhiy-storchaka already pointed out, "proportional memory already spent on the input string and proportional time was already spent on reading and decoding it").

And, It should not be labelled "Type-Security" .

Point to note : this PR is relevant to issue - #128840 , but it doesn't entirely fix the issue.
The issue is

IPv6 addresses have a maximum length (8 colon-separated parts) but the current implementation doesn't limit the length.

This fix just limits the number of : in the address, not the entire address length. A string like this would still be relavant to the issue, and would not be fixed by this.

'0000::' + '0'*(10**4)

And, a complete fix would maybe add a check in _ip_int_from_string method for length of ip_str to be less than or equal to 39 (0000:0000:0000:0000:0000:0000:0000:0000)

This check could come in the __init__ method of IPv6Address class, but that might not be the best place for it.

@lazysegtree I've made the updates to limit total number of characters in addition to number of splits.

(Updated from main to fix the unrelated docs CI failure.)

LGTM. 👍

All commit authors signed the Contributor License Agreement.

Thanks @sethmlarson for the PR, and @gpshead for merging it 🌮🎉.. I'm working now to backport this PR to: 3.9, 3.10, 3.11, 3.12, 3.13, 3.14.
🐍🍒⛏🤖

…ythonGH-128841) pythonGH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

GH-134610 is a backport of this pull request to the 3.14 branch.

…ythonGH-128841) pythonGH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

GH-134611 is a backport of this pull request to the 3.13 branch.

GH-134612 is a backport of this pull request to the 3.12 branch.

…ythonGH-128841) pythonGH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

GH-134613 is a backport of this pull request to the 3.11 branch.

…ythonGH-128841) pythonGH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

GH-134614 is a backport of this pull request to the 3.10 branch.

…ythonGH-128841) pythonGH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

GH-134615 is a backport of this pull request to the 3.9 branch.

…H-128841) (#134610) gh-128840: Limit the number of parts in IPv6 address parsing (GH-128841) GH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

…H-128841) (#134611) gh-128840: Limit the number of parts in IPv6 address parsing (GH-128841) GH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

…H-128841) (#134612) gh-128840: Limit the number of parts in IPv6 address parsing (GH-128841) GH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

…H-128841) (GH-134613) Limit length of IP address string to 39 (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

…H-128841) (GH-134614) Limit length of IP address string to 39 (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

…H-128841) (GH-134615) Limit length of IP address string to 39 (cherry picked from commit 47f1161) Co-authored-by: Seth Michael Larson <seth@python.org> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

…ythonGH-128841) pythonGH-128840: Limit the number of parts in IPv6 address parsing Limit length of IP address string to 39 --------- Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Serhiy Storchaka <storchaka@gmail.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>

pythonGH-128840 : Limit the number of parts in IPv6 address parsing

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sethmlarson added the type-security A security issue label Jan 14, 2025

bedevere-app Bot mentioned this pull request Jan 14, 2025

IPv6 address parsing doesn't limit buffer size #128840

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sethmlarson added 2 commits January 14, 2025 11:19

Add news entry

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Fix location of new test case

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MarkusH approved these changes Jan 14, 2025

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nessita approved these changes Jan 14, 2025

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sethmlarson requested a review from serhiy-storchaka January 14, 2025 19:41

gpshead added needs backport to 3.9 needs backport to 3.11 only security fixes needs backport to 3.12 only security fixes needs backport to 3.13 only security fixes labels Jan 14, 2025

serhiy-storchaka reviewed Jan 14, 2025

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Comment thread Misc/NEWS.d/next/Security/2025-01-14-11-19-07.gh-issue-128840.M1doZW.rst Outdated

Update with more descriptive news

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serhiy-storchaka reviewed Jan 15, 2025

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Comment thread Misc/NEWS.d/next/Security/2025-01-14-11-19-07.gh-issue-128840.M1doZW.rst Outdated

Limit length of IP address string to 39

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Merge branch 'main' into ipv6-address-parts

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Merge branch 'main' into ipv6-address-parts

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serhiy-storchaka approved these changes Apr 14, 2025

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bedevere-app Bot added awaiting merge and removed awaiting core review labels Apr 14, 2025

gpshead merged commit 47f1161 into python:main May 24, 2025

bedevere-app Bot removed the awaiting merge label May 24, 2025

bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label May 24, 2025

bedevere-app Bot removed the needs backport to 3.13 only security fixes label May 24, 2025

bedevere-app Bot removed the needs backport to 3.12 only security fixes label May 24, 2025

bedevere-app Bot removed the needs backport to 3.11 only security fixes label May 24, 2025

bedevere-app Bot removed the needs backport to 3.10 label May 24, 2025

bedevere-app Bot removed the needs backport to 3.9 label May 24, 2025

gh-128840: Limit the number of parts in IPv6 address parsing by sethmlarson · Pull Request #128841 · python/cpython · GitHub

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gh-128840: Limit the number of parts in IPv6 address parsing - #128841

gh-128840: Limit the number of parts in IPv6 address parsing#128841gpshead merged 9 commits intopython:mainpython/cpython:mainfrom sethmlarson:ipv6-address-partssethmlarson/cpython:ipv6-address-partsCopy head branch name to clipboard

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gh-128840: Limit the number of parts in IPv6 address parsing#128841
gpshead merged 9 commits into
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sethmlarson:ipv6-address-parts

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