On Mon 24-04-23 09:27:00, Dmitry Vyukov wrote: > On Mon, 24 Apr 2023 at 09:19, syzbot > <syzbot+4a03518df1e31b537066@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 44149752e998 Merge tag 'cgroup-for-6.3-rc6-fixes' of git:/.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=100db37bc80000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=710057cbb8def08c > > dashboard link: https://syzkaller.appspot.com/bug?extid=4a03518df1e31b537066 > > compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/7bfa303f05cc/disk-44149752.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/4e8ea8730409/vmlinux-44149752.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/e584bce13ba7/bzImage-44149752.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+4a03518df1e31b537066@xxxxxxxxxxxxxxxxxxxxxxxxx > > The race is here: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/ext4/extents_status.c?id=44149752e9987a9eac5ad78e6d3a20934b5e018d#n271 > > If I am reading this correctly, it can lead to returning a wrong > extent if tree->cache_es is re-read after the range check. > I think tree->cache_es read/write should use READ/WRITE_ONCE. Right. I'll send a fix. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
