Messages in this thread | | | Subject | Re: [syzbot] KFENCE: use-after-free in kvm_fastop_exception | From | Matthieu Baerts <> | Date | Wed, 18 Aug 2021 10:21:51 +0200 |
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Hi Pavel,
On 18/08/2021 10:12, Pavel Skripkin wrote: > On 8/18/21 11:02 AM, Matthieu Baerts wrote: >> Hello, >> >> On 18/08/2021 00:21, syzbot wrote: >>> syzbot has bisected this issue to: >>> >>> commit c4512c63b1193c73b3f09c598a6d0a7f88da1dd8 >>> Author: Matthieu Baerts <matthieu.baerts@tessares.net> >>> Date: Fri Jun 25 21:25:22 2021 +0000 >>> >>> mptcp: fix 'masking a bool' warning >>> >>> bisection log: >>> https://syzkaller.appspot.com/x/bisect.txt?x=122b0655300000 >>> start commit: b9011c7e671d Add linux-next specific files for 20210816 >>> git tree: linux-next >>> final oops: >>> https://syzkaller.appspot.com/x/report.txt?x=112b0655300000 >>> console output: https://syzkaller.appspot.com/x/log.txt?x=162b0655300000 >>> kernel config: >>> https://syzkaller.appspot.com/x/.config?x=a245d1aa4f055cc1 >>> dashboard link: >>> https://syzkaller.appspot.com/bug?extid=7b938780d5deeaaf938f >>> syz repro: >>> https://syzkaller.appspot.com/x/repro.syz?x=157a41ee300000 >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14f78ff9300000 >> >> I'm pretty sure the commit c4512c63b119 ("mptcp: fix 'masking a bool' >> warning") doesn't introduce the reported bug. This minor fix is specific >> to MPTCP which doesn't seem to be used here. >> >> I'm not sure how I can tell syzbot this is a false positive. >> > > > looks like it's fs/namei bug. Similar reports: > > https://syzkaller.appspot.com/bug?id=517fa734b92b7db404c409b924cf5c997640e324 > > > https://syzkaller.appspot.com/bug?id=484483daf3652b40dae18531923aa9175d392a4d
Thank you for having checked! Should we mark them as "#syz dup" if you think they have the same root cause?
> It's not false positive. I've suggested the fix here: > https://groups.google.com/g/syzkaller-bugs/c/HE3c2fP5nic/m/1Yk17GBeAwAJ > I am waiting for author comments about the fix :) > > But, yes, syzbot bisection is often wrong, so don't rely on it much :)
Yes sorry, I wanted to say the bisection picked a wrong commit :)
All good then if syzbot often blames the wrong modification :)
Cheers, Matt -- Tessares | Belgium | Hybrid Access Solutions www.tessares.net
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