On Tue, Sep 19, 2023 at 10:25:22PM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: e42bebf6db29 Merge tag 'efi-fixes-for-v6.6-1' of git://git.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=179f4a38680000 > kernel config: https://syzkaller.appspot.com/x/.config?x=df91a3034fe3f122 > dashboard link: https://syzkaller.appspot.com/bug?extid=9cf75dc581fb4307d6dd > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1374a174680000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b12928680000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/14a6a5d23944/disk-e42bebf6.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/98cc4c220388/vmlinux-e42bebf6.xz > kernel image: https://storage.googleapis.com/syzbot-assets/6a1d09cf21bf/bzImage-e42bebf6.xz > mounted in repro #1: https://storage.googleapis.com/syzbot-assets/37e5beb24789/mount_0.gz > mounted in repro #2: https://storage.googleapis.com/syzbot-assets/f219a9e665e9/mount_8.gz > > The issue was bisected to: > > commit b81427939590450172716093dafdda8ef52e020f > Author: Eric Biggers <ebiggers@xxxxxxxxxx> > Date: Mon Aug 14 18:29:02 2023 +0000 > > ext4: remove redundant checks of s_encoding > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10852352680000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=12852352680000 > console output: https://syzkaller.appspot.com/x/log.txt?x=14852352680000 This report is expected for now, since the repro involves writing to the page cache of a mounted block device. For more information see https://lore.kernel.org/linux-fsdevel/20230813001202.GE41642@sol.localdomain and https://lore.kernel.org/linux-fsdevel/20230814182903.37267-2-ebiggers@xxxxxxxxxx. Also https://lore.kernel.org/linux-fsdevel/20230704122727.17096-1-jack@xxxxxxx which will ultimately be the fix for this class of issue. Note: the repro that syzkaller generated for this is very strange (even moreso than usual for syzkaller repros...) because it replaces its "scratch space" at address 0x20000000 with a different mapping, specifically a mapping for a file that is mounted as a filesystem via loopback. That makes "syscalls" have weird side effects as a result of the repro writing parameters to the address that is supposed to contain its scratch space. I don't think this should be happening, so I've opened https://github.com/google/syzkaller/issues/4216 for it. - Eric
