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Bug#1115729: Stable fix request: error in internal cancellation syscall handling, corrupting copy_file_range syscall return value



On 2025-11-16 04:51, Daniel Shahaf wrote:
> Joel Johnson wrote on Fri, Sep 19, 2025 at 08:45:10 -0600:
> > Package: libc
> > Version: 2.41-12
> > Severity: grave
> > 
> > (Marking as grave since it leads to data loss)
> > 
> > An issue has been identified and fixed upstream causing data loss using
> > copy_file_range. It is most prominent with OpenZFS but also appears to have
> > potential impacts on FUSE. I would request that this be patched for a trixie
> > update. I didn't see any existing issue for this, apologies if it's a
> > duplicate.
> > 
> > https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=7107bebf19286f42dcb0a97581137a5893c16206
> > 
> > https://sourceware.org/bugzilla/show_bug.cgi?id=33245
> > 
> > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=79139
> 
> Morning.  I haven't run into the buggy behaviour, but I did run into
> this ticket in the apt-listchanges(1) output during an upgrade, and I'm
> not sure whether the bug would impact me if I proceeded with the upgrade.
> 
> Two questions:
> 
> 1. Considering this bug is described as "data loss" and appears in
>    apt-listchanges(1) output for folks upgrading oldstable→stable, could
>    someone please summarize situations in which the bug is known /not/
>    to occur even under 2.41-12 (currently in trixie)?
>    
>    I'm not asking for an exhaustive list; just for common known-good
>    scenarios.  Something of the form "It's safe to upgrade to trixie and
>    glibc/2.41-12 as long as you don't do X, Y, or Z" would be great.

The bugs does not appear with usual filesystems like ext4 or xfs.

> 2. The bug is fixed in 2.41-2 in experimental, but hasn't yet been fixed

Actually in 2.42-2.

>    in either sid or trixie (as requested by the OP).  Is the bug
>    expected to be fixed in trixie?

Yes, this is planned, but it has to be fixed before being able to fix 
it in trixie.

>    I'm not sure what blocks 2.42 from being uploaded to sid.

The plan was indeed to stop the maintenance of 2.41 in sid and upload 
2.42 to sid. A lot of effort has been put on preparing 2.42, including 
an archive rebuild. Unfortunately this is currently blocked by #1115881 
with no answer from the Ada maintainers...

After that I lost all my motivation to work on glibc. I guess, I'll try 
to upload a new 2.41 version to sid, so that we can fix the bug in 
trixie...

>    I've verified the patch above (7107bebf19286f42dcb0a97581137a5893c16206)
>    applies cleanly to the version in trixie.  I've tried to build it,
>    too; the build didn't actually pass, but at least it failed in the
>    same way with the patch and without it, and the failure may well be
>    unrelated to the patch.  (I was building in a new trixie chroot.)

Yes, this is likely unrelated, and probably depends on the way your 
chroot is setup. The best is to use the unshare feature of sbuild which 
provide a reproducible environment. You have to look at the output file 
of the individual errors (which should be dumped earlier in the build 
log) to understand the issue.

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net


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