Horton

Add timingsafe_bcmp(), for constant-time memory comparison

Heikki Linnakangas <heikki.linnakangas@iki.fi>

View on postgr.es
Commit: b282280e9b69cae988c0c69cce3eda4d4bd38fff
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Committer: Noah Misch <noah@leadboat.com>
Date: 2026-05-11T12:13:51Z
Releases: 14.23 
Add timingsafe_bcmp(), for constant-time memory comparison

timingsafe_bcmp() should be used instead of memcmp() or a naive
for-loop, when comparing passwords or secret tokens, to avoid leaking
information about the secret token by timing. This commit just
introduces the function but does not change any existing code to use
it yet.

This has been initially applied as of 09be39112654 in v18 and newer
versions, and will be used in all the stable branches for an upcoming
fix.

Co-authored-by: Jelte Fennema-Nio <github-tech@jeltef.nl>
Discussion: https://www.postgresql.org/message-id/7b86da3b-9356-4e50-aa1b-56570825e234@iki.fi
Security: CVE-2026-6478
Backpatch-through: 14

Files

PathChange+/−
configure modified +23 −0
configure.ac modified +2 −1
src/include/pg_config.h.in modified +7 −0
src/include/port.h modified +4 −0
src/port/timingsafe_bcmp.c added +43 −0
src/tools/msvc/Mkvcbuild.pm modified +1 −1
src/tools/msvc/Solution.pm modified +2 −0

Discussion