syncthing package is vulnerable to CVE-2021-21404

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2 participants
  • Leo Famulari
  • Léo Le Bouter
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Léo Le Bouter
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Léo Le Bouter wrote on 7 Apr 2021 00:40
(address . bug-guix@gnu.org)
38a8a1cb8749b422642dfa6d5374c242ddb80b42.camel@zaclys.net
CVE-2021-21404 06.04.21 22:15
Syncthing is a continuous file synchronization program. In Syncthing
before version 1.15.0, the relay server `strelaysrv` can be caused to
crash and exit by sending a relay message with a negative length field.
Similarly, Syncthing itself can crash for the same reason if given a
malformed message from a malicious relay server when attempting to join
the relay. Relay joins are essentially random (from a subset of low
latency relays) and Syncthing will by default restart when crashing, at
which point it's likely to pick another non-malicious relay. This flaw
is fixed in version 1.15.0.

We still ship 1.5.0, we crucially need to update that *very* useful
networked daemon package. With the new go importer maybe that's easier.
Also work in the go build system needs to happen IIRC.

Previous discussion about updating syncthing:

Léo
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Léo Le Bouter wrote on 7 Apr 2021 00:41
(address . control@debbugs.gnu.org)
e680139bcfbd4cb950c09bd4bb6c82d109a89707.camel@zaclys.net
tags 47627 + security
quit
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Leo Famulari wrote on 7 Apr 2021 00:51
(name . Léo Le Bouter via Bug reports for GNU Guix)(address . bug-guix@gnu.org)(address . 47627@debbugs.gnu.org)
YGzmAwp2zOS9lTD6@jasmine.lan
On Wed, Apr 07, 2021 at 12:40:03AM +0200, Léo Le Bouter via Bug reports for GNU Guix wrote:
Toggle quote (18 lines)
> CVE-2021-21404 06.04.21 22:15
> Syncthing is a continuous file synchronization program. In Syncthing
> before version 1.15.0, the relay server `strelaysrv` can be caused to
> crash and exit by sending a relay message with a negative length field.
> Similarly, Syncthing itself can crash for the same reason if given a
> malformed message from a malicious relay server when attempting to join
> the relay. Relay joins are essentially random (from a subset of low
> latency relays) and Syncthing will by default restart when crashing, at
> which point it's likely to pick another non-malicious relay. This flaw
> is fixed in version 1.15.0.
>
> We still ship 1.5.0, we crucially need to update that *very* useful
> networked daemon package. With the new go importer maybe that's easier.
> Also work in the go build system needs to happen IIRC.
>
> Previous discussion about updating syncthing:
> https://issues.guix.gnu.org/45476

Yeah. Given this report, we could also just build Syncthing with the
bundled source code, which is freely licensed.
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Leo Famulari wrote on 9 Apr 2021 02:01
(name . Léo Le Bouter via Bug reports for GNU Guix)(address . bug-guix@gnu.org)(address . 47627@debbugs.gnu.org)
YG+ZVl0SMWko4LOJ@jasmine.lan
On Tue, Apr 06, 2021 at 06:51:47PM -0400, Leo Famulari wrote:
Toggle quote (3 lines)
> Yeah. Given this report, we could also just build Syncthing with the
> bundled source code, which is freely licensed.

I've attached the patch.
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Léo Le Bouter wrote on 12 Apr 2021 02:27
1594339afcb287329f672249f6ae8ad89e8dbba3.camel@zaclys.net
On Thu, 2021-04-08 at 20:01 -0400, Leo Famulari wrote:
Toggle quote (7 lines)
> On Tue, Apr 06, 2021 at 06:51:47PM -0400, Leo Famulari wrote:
> > Yeah. Given this report, we could also just build Syncthing with
> > the
> > bundled source code, which is freely licensed.
>
> I've attached the patch.

I tested this patch on my system, works great with the syncthing
service also. LGTM from me.
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Leo Famulari wrote on 12 Apr 2021 03:54
(name . Léo Le Bouter)(address . lle-bout@zaclys.net)(address . 47627-done@debbugs.gnu.org)
YHOobxPF9OMoiv7C@jasmine.lan
On Mon, Apr 12, 2021 at 02:27:51AM +0200, Léo Le Bouter wrote:
Toggle quote (11 lines)
> On Thu, 2021-04-08 at 20:01 -0400, Leo Famulari wrote:
> > On Tue, Apr 06, 2021 at 06:51:47PM -0400, Leo Famulari wrote:
> > > Yeah. Given this report, we could also just build Syncthing with
> > > the
> > > bundled source code, which is freely licensed.
> >
> > I've attached the patch.
>
> I tested this patch on my system, works great with the syncthing
> service also. LGTM from me.

Thanks for the review. Pushed as
ed3ef756f521a0df8596a88b66f65b7a1ad99252
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