Here are some information:

It crashes when specific files are scanned. However, but it is unlikely
that the file contains the bad signature (but im not sure). I have a sample
file, but with personal data that I cannot share. Yesterday I was able to
reproduce the crash, but today I no longer have the version 26908. If you
send me the version of yesterday and describe what you need, I can try to
debug something.

Here is my test from yesterday with version 0.103.8 on gentoo:

# clamscan clamav-0c216ef050250d78d59408a83f383ba1.tmp
LibClamAV Warning: Don't know how to create filter for:
Win.Downloader.LNKAgent-10001628-0
LibClamAV Warning: cli_ac_addpatt: cannot use filter for trie
Segmentation fault

# echo "Win.Downloader.LNKAgent-10001628-0" > /var/lib/clamav/bad_sig.ign2

# clamscan clamav-0c216ef050250d78d59408a83f383ba1.tmp
clamav-0c216ef050250d78d59408a83f383ba1.tmp: OK

The LibClamAV Warnings also came when scanning other files, but other files
was successfully scanned without any crash.

clamscan[26247]: segfault at 7fd6907960bf ip 00007fd5e36947a7 sp
00007ffe80983900 error 4 in libclamav.so.9.0.5[7fd5e3692000+116000] likely
on CPU 0 (core 0, socket 0)

Hope this helps to find the problem.

PS: Thanks to my lifesaver Matthias for the tip about the whitelist
yesterday.

Mario

Am Di., 16. Mai 2023 um 14:51 Uhr schrieb Matthias Rieber <
matthias+cla...@zu-con.org>:

> Hello,
>
> On Tue, 16 May 2023, Ralf Hildebrandt via clamav-users wrote:
>
> >> As far as I can tell this happens in
> >>
> >> 0x7fdfd44c377d <ac_backward_match_branch+813>
> >>
> >> We use version 0.103.8+dfsg-0+deb11u1 on debian bullseye.
> >>
> >> Has anyone seen this, too?
> >
> > I've seen this with 1.1.0-1 as well. Maybe they're related to the
> > "pattern issue" I posted a while ago
>
> yes, it turns out that you can mitigate this issue when you whitelist
> this signature:
>
> $ echo "Win.Downloader.LNKAgent-10001628-0" > /var/lib/clamav/bad_sig.ign2
>
> Regards,
> Matthias
>
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