On Wed, Jan 27, 2021 at 7:46 PM 'Andrey Konovalov' via syzkaller-bugs <[email protected]> wrote: > > On Wed, Jan 27, 2021 at 6:24 PM Dmitry Vyukov <[email protected]> wrote: > > > > On Wed, Jan 27, 2021 at 6:15 PM Will Deacon <[email protected]> wrote: > > > > > > On Wed, Jan 27, 2021 at 06:00:30PM +0100, Dmitry Vyukov wrote: > > > > On Wed, Jan 27, 2021 at 5:56 PM syzbot > > > > <[email protected]> wrote: > > > > > > > > > > Hello, > > > > > > > > > > syzbot found the following issue on: > > > > > > > > > > HEAD commit: 2ab38c17 mailmap: remove the "repo-abbrev" comment > > > > > git tree: upstream > > > > > console output: > > > > > https://syzkaller.appspot.com/x/log.txt?x=15a25264d00000 > > > > > kernel config: > > > > > https://syzkaller.appspot.com/x/.config?x=ad43be24faf1194c > > > > > dashboard link: > > > > > https://syzkaller.appspot.com/bug?extid=45b6fce29ff97069e2c5 > > > > > userspace arch: arm64 > > > > > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the > > > > > commit: > > > > > Reported-by: [email protected] > > > > > > > > This happens on arm64 instance with mte enabled. > > > > There is a GPF in reiserfs_xattr_init on x86_64 reported: > > > > https://syzkaller.appspot.com/bug?id=8abaedbdeb32c861dc5340544284167dd0e46cde > > > > so I would assume it's just a plain NULL deref. Is this WARNING not > > > > indicative of a kernel bug? Or there is something special about this > > > > particular NULL deref? > > > > > > Congratulations, you're the first person to trigger this warning! > > > > > > This fires if we take an unexpected data abort in the kernel but when we > > > get into the fault handler the page-table looks ok (according to the CPU > > > via > > > an 'AT' instruction). Are you using QEMU system emulation? Perhaps its > > > handling of AT isn't quite right. > > > > Hi Will, > > > > Yes, it's qemu-system-aarch64 5.2 with -machine virt,mte=on -cpu max. > > Do you see any way forward for this issue? Can somehow prove/disprove > > it's qemu at fault? > > I've reproduced this crash (by taking [1] and changing > sys_memfd_create to 279), but it manifests as a normal null-ptr-deref > for me. I'm using the latest QEMU master. Which QEMU does syzbot use > exactly?
qemu-system-aarch64 5.2 from this container: https://github.com/google/syzkaller/blob/master/tools/docker/syzbot/Dockerfile you can get a prebuilt version with: docker pull gcr.io/syzkaller/syzbot > [1] https://syzkaller.appspot.com/text?tag=ReproC&x=14d3621cd00000 > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/CAAeHK%2ByWe_GRDi8j7aPZAauTrfdjgYpYoj9F_KrsG3vtHDwTsw%40mail.gmail.com.
