On Wed, May 29, 2019 at 5:27 PM Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, May 29, 2019 at 05:14:17PM +0200, Dmitry Vyukov wrote: > > > > > It looks like > > > > > > ommit 1515a63fc413f160d20574ab0894e7f1020c7be2 > > > Author: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx> > > > Date: Wed Apr 3 23:27:24 2019 +0300 > > > > > > net: bridge: always clear mcast matching struct on reports and leaves > > > > > > may have at least fixed the uninitialised value error. > > > > > > The most up-to-date info is always available here: > > > > >> dashboard link: https://syzkaller.appspot.com/bug?extid=bc5ab0af2dbf3b0ae897 > > > > It says no new crashes happened besides the original one. > > > > We now have the following choices: > > > > 1. Invalidate with "#syz invalid" > > 2. Mark as tentatively fixed by that commit (could it fix it?) with > > "#syz fix: net: bridge: always clear mcast matching struct on reports > > and leaves" > > 3. Do nothing, then syzbot will auto-close it soon (bugs without > > reproducers that did not happen in the past 180 days) > > I'm still not quite sure how this could cause the use-after-free, > but it certainly seems to be the cause for the second issue of > uninit-value: > > https://syzkaller.appspot.com/bug?extid=8dfe5ee27aa6d2e396c2 > > And this one does seem to have occured again recently (two months > ago). I've closed the KMSAN bug report with this commit. And since the uninit value was used inside of the rhashtable (as hash?) it could lead to any kind of inconsistencies, I guess we can do: #syz fix: net: bridge: always clear mcast matching struct on reports and leaves here too. Thanks for bringing this up!
