On Sun, Oct 20, 2024 at 05:08:45PM +0000, Piotr Zalewski wrote: > In bch2_fs_initialize if bch2_trans_mark_dev_sbs fails, set freespace > initialized bits to 0 in member's flags and update member cached version > for each device. bch2_trans_mark_dev_sbs fails just before freespace > init which can left freespace init bits set to true erroneously which later > can indirectly trigger BUG condition in bch2_bucket_alloc_freelist[1].
Err... freespace_initialized shouldn't even be set at this point, it's set later, in bch2_fs_freespace_init(), naturally. So - syzbot is feeding us garbage, heh. BCH_MEMBER_FREESPACE_INITIALIZED should be false on a non initialized filesystem. So we actually should be unconditially clearing it (sanitizing our input) at the top of bch2_fs_initialize(). > > [1] https://syzkaller.appspot.com/bug?extid=2b6a17991a6af64f9489 > > Reported-by: [email protected] > Closes: https://syzkaller.appspot.com/bug?extid=2b6a17991a6af64f9489 > Fixes: bbe682c76789 ("bcachefs: Ensure devices are always correctly > initialized") > Signed-off-by: Piotr Zalewski <[email protected]> > --- > fs/bcachefs/recovery.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c > index 67bba156cce9..bcec79122f65 100644 > --- a/fs/bcachefs/recovery.c > +++ b/fs/bcachefs/recovery.c > @@ -1031,6 +1031,7 @@ int bch2_fs_initialize(struct bch_fs *c) > struct bkey_inode_buf packed_inode; > struct qstr lostfound = QSTR("lost+found"); > int ret; > + struct bch_member *m; > > bch_notice(c, "initializing new filesystem"); > set_bit(BCH_FS_new_fs, &c->flags); > @@ -1086,8 +1087,17 @@ int bch2_fs_initialize(struct bch_fs *c) > bch_verbose(c, "marking superblocks"); > ret = bch2_trans_mark_dev_sbs(c); > bch_err_msg(c, ret, "marking superblocks"); > - if (ret) > + if (ret) { > + mutex_lock(&c->sb_lock); > + for_each_member_device(c, ca) { > + m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx); > + SET_BCH_MEMBER_FREESPACE_INITIALIZED(m, false); > + ca->mi = bch2_mi_to_cpu(m); > + } > + mutex_unlock(&c->sb_lock); > + > goto err; > + } > > for_each_online_member(c, ca) > ca->new_fs_bucket_idx = 0; > -- > 2.47.0 > >
