Ubuntu
libdfp package

libdfp: FTBFS with glibc 2.39 snapshot

Bug #2049897 reported by Ravi Kant Sharma
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
glibc (Ubuntu)
Invalid
High
Simon Chopin
libdfp (Ubuntu)
Fix Released
Undecided
Unassigned

Bug Description

During the recent test rebuilds, one of the rebuild configurations was against a snapshot of the upcoming glibc 2.39.

libdfp failed to build in that configuration with the error.

Segmentation fault (core dumped)

This has been confirmed locally with a more recent snapshot.

See https://launchpad.net/ubuntu/+archive/test-rebuild-20231215-noble-glibc/+build/27491681/+files/buildlog_ubuntu-noble-amd64.libdfp_1.0.16-1_BUILDING.txt.gz for full logs, https://people.canonical.com/~ginggs/ftbfs-report/test-rebuild-20231215-noble-glibc-noble.html for the glibc rebuild report, and https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/glibc for the most recent glibc snapshot.

Simon Chopin (schopin)
tags: added: foundations-todo
Changed in glibc (Ubuntu):
importance: Undecided → High
status: New → Triaged
assignee: nobody → Simon Chopin (schopin)
Simon Chopin (schopin)
Changed in glibc (Ubuntu):
status: Triaged → In Progress
Revision history for this message
Simon Chopin (schopin) wrote :

My initial suspect was 5c37d2065286d3db7b974266a3002bb5747d2e5d (vfprintf-internal: Get rid of alloca.) in glibc. However, carefully reading through the code I couldn't find anything fundamentally wrong with the new code. Worse, I'm still unable to reproduce as standalone C code.

However, something interesting happened: it works fine when compiling the library using -O0. This could mean that the libdfp code is invoking some UB somewhere.

Still working on it.

Revision history for this message
Simon Chopin (schopin) wrote :

This ended up being fixed in the upstream libdfp, I pushed a patched version in the archive, currently in -proposed.

Changed in libdfp (Ubuntu):
status: New → Fix Committed
Changed in glibc (Ubuntu):
status: In Progress → Invalid
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package libdfp - 1.0.16-1ubuntu1

---------------
libdfp (1.0.16-1ubuntu1) noble; urgency=medium

  * Fix the printf handler on GCC14/glibc 2.39 (LP: #2049897)

 -- Simon Chopin <email address hidden> Tue, 12 Mar 2024 10:00:56 +0100

Changed in libdfp (Ubuntu):
status: Fix Committed → Fix Released
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