Differential D8202

[SECP256K1] Return NULL early in context_preallocated_create if flags invalid
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Authored by Fabien on Oct 30 2020, 19:35.

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Reviewers

deadalnix

Group Reviewers

Restricted Project

Commits

rABC9acf260b37c1: [SECP256K1] Return NULL early in context_preallocated_create if flags invalid

Summary

If the user passes invalid flags to _context_create, and the default
illegal callback does not abort the program (which is possible), then we
work with the result of malloc(0), which may be undefined behavior. This
violates the promise that a library function won't crash after the
illegal callback has been called.

This commit fixes this issue by returning NULL early in _context_create
in that case.

Backport of secp256k1 PR840.

Test Plan

ninja check-secp256k1

Diff Detail

Repository

rABC Bitcoin ABC

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Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

Fabien created this revision.Oct 30 2020, 19:35

Herald added a reviewer: Restricted Project. · View Herald TranscriptOct 30 2020, 19:36

Fabien requested review of this revision.Oct 30 2020, 19:36

teamcity edited the summary of this revision. (Show Details)Oct 30 2020, 19:36

Harbormaster completed remote builds in B13779: Diff 25294.Oct 30 2020, 20:05

Fabien retitled this revision from Return NULL early in context_preallocated_create if flags invalid to [SECP256K1] Return NULL early in context_preallocated_create if flags invalid.Oct 30 2020, 21:09

deadalnix accepted this revision.Oct 30 2020, 22:29

This revision is now accepted and ready to land.Oct 30 2020, 22:29

Closed by commit rABC9acf260b37c1: [SECP256K1] Return NULL early in context_preallocated_create if flags invalid (authored by Tim Ruffing <crypto@timruffing.de>, committed by Fabien). · Explain WhyOct 31 2020, 10:13

This revision was automatically updated to reflect the committed changes.

Fabien added a commit: rABC9acf260b37c1: [SECP256K1] Return NULL early in context_preallocated_create if flags invalid.