* Aleksandr Nogikh <nogikh@xxxxxxxxxx> [241118 08:13]: > Hi Liam, > > On Mon, Nov 18, 2024 at 3:49 AM 'Liam R. Howlett' via syzkaller-bugs > <syzkaller-bugs@xxxxxxxxxxxxxxxx> wrote: > > > > * syzbot <syzbot+bc6bfc25a68b7a020ee1@xxxxxxxxxxxxxxxxxxxxxxxxx> [241117 05:42]: > > > Hello, > > > > > > syzbot found the following issue on: > > > > > > HEAD commit: 8e9a54d7181b Merge remote-tracking branch 'iommu/arm/smmu'.. > > > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > > > console output: https://syzkaller.appspot.com/x/log.txt?x=17b0ace8580000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=a1eb85a42cb8ccec > > > dashboard link: https://syzkaller.appspot.com/bug?extid=bc6bfc25a68b7a020ee1 > > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > > userspace arch: arm64 > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=147521a7980000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=102e14c0580000 > > > > > > Downloadable assets: > > > disk image: https://storage.googleapis.com/syzbot-assets/ad658fb4d0a2/disk-8e9a54d7.raw.xz > > > vmlinux: https://storage.googleapis.com/syzbot-assets/1b7754fa8c67/vmlinux-8e9a54d7.xz > > > kernel image: https://storage.googleapis.com/syzbot-assets/50315382fefb/Image-8e9a54d7.gz.xz > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+bc6bfc25a68b7a020ee1@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > I was unable to get this reproducer to work on my own image, even using > > the config and compiler specified in the report. The injection was not > > happening at the same location as the crash reports. > > > > After using the provided disk (which was tricky), I was able to get it > > to work. > > Just in case: did you follow the official syzbot instructions on > reproducing the bugs from the attached assets? [1] If yes, what extra > information could have made the process simpler for you? > > [1] https://github.com/google/syzkaller/blob/master/docs/syzbot_assets.md The instructions on getting the source we need (without adding yet another remote and fetching the entire repo) would help, as well as booting the kernel. ie: --kernel <file> --append <root=...> The missing part for me was that the commit listed was already gone, so after Lorenzo responded and restested with code in the repo, I could pull the kernel. Maybe I could have just fetched the ref somehow? So these instructions are good. I didn't see them in the emails or on the dashboard though? Booting my own kernel ended up in panics about the rootfs missing, and some fool around with that. > > > Booting was painfully slow, and makes me wonder if there is a > > better way for reproducing issues in the future. > > I guess that unless you run it on an arm64 device with a nested > virtualization support, this bug's reproduction will be slow anyway :( The initial boot of arm64 seems to just sit around for a while thinking about booting. My installed vm was using uefi, which turned out to also be a pain point. > > If you recompile the kernel image without CONFIG_KASAN and > CONFIG_KCOV, that should speed it up to some degree. I think arm64 on amd64 is just slow, but thanks. kasan seems necessary a lot of the time. Regards, Liam
