Hi Alan, On Wednesday, October 23rd, 2024 at 9:33 AM, Alan Huang <[email protected]> wrote:
> On Oct 23, 2024, at 15:21, Piotr Zalewski [email protected] wrote: > > > Add NULL check for key returned from bch2_btree_and_journal_iter_peek in > > btree_node_iter_and_journal_peek to avoid NULL ptr dereference in > > bch2_bkey_buf_reassemble. > > > It would be helpful if the commit message explained why k.k is null in this > case I will debug this more thoroughly and provide details. For now I see that during GC it sees journal replay hasn't finished but journal turns out to be empty? Which seems weird, so maybe underlying issue should be solved on a deeper level. Log from the reproducer is: ``` [ 27.391332] bcachefs (loop0): accounting_read... done [ 27.408141] bcachefs (loop0): alloc_read... done [ 27.409118] bcachefs (loop0): stripes_read... done [ 27.410059] bcachefs (loop0): snapshots_read... done [ 27.411161] bcachefs (loop0): check_allocations... [ 27.415003] bucket 0:26 data type btree ptr gen 0 missing in alloc btree [ 27.415024] while marking u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq ac62141f8dc7e261 written 24 min_kg [ 27.422560] bucket 0:38 data type btree ptr gen 0 missing in alloc btree [ 27.422571] while marking u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 7589ab5e0c11cc7a written 24 min_kg [ 27.428033] bucket 0:41 data type btree ptr gen 0 missing in alloc btree [ 27.428042] while marking u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 9aa2895aefce4bdf written 24 min_kg [ 27.432315] bcachefs (loop0): btree topology error: attempting to get btree node with non-btree key u64s 0 type [ 27.435343] bcachefs (loop0): inconsistency detected - emergency read only at journal seq 10 [ 27.436947] bcachefs (loop0): bch2_gc_btree(): error btree_need_topology_repair [ 27.438756] btree node read error for xattrs, shutting down [ 27.440081] bcachefs (loop0): bch2_gc_btrees(): error fsck_errors_not_fixed [ 27.441915] bcachefs (loop0): bch2_check_allocations(): error fsck_errors_not_fixed [ 27.443349] bcachefs (loop0): bch2_fs_recovery(): error fsck_errors_not_fixed [ 27.444802] bcachefs (loop0): bch2_fs_start(): error starting filesystem fsck_errors_not_fixed [ 27.446270] bcachefs (loop0): shutting down [ 27.456042] bcachefs (loop0): shutdown complete [ 27.835683] bcachefs: bch2_fs_get_tree() error: fsck_errors_not_fixed ``` > > Reported-by: [email protected] > > Closes: https://syzkaller.appspot.com/bug?extid=005ef9aa519f30d97657 > > Fixes: 5222a4607cd8 ("bcachefs: BTREE_ITER_WITH_JOURNAL") > > Signed-off-by: Piotr Zalewski [email protected] > > --- > > fs/bcachefs/btree_iter.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c > > index 0883cf6e1a3e..625167ce191f 100644 > > --- a/fs/bcachefs/btree_iter.c > > +++ b/fs/bcachefs/btree_iter.c > > @@ -882,6 +882,8 @@ static noinline int > > btree_node_iter_and_journal_peek(struct btree_trans *trans, > > __bch2_btree_and_journal_iter_init_node_iter(trans, &jiter, l->b, l->iter, > > path->pos); > > > > k = bch2_btree_and_journal_iter_peek(&jiter); > > + if (!k.k) > > + goto err; > > > > bch2_bkey_buf_reassemble(out, c, k); > > > > @@ -889,6 +891,7 @@ static noinline int > > btree_node_iter_and_journal_peek(struct btree_trans *trans, > > c->opts.btree_node_prefetch) > > ret = btree_path_prefetch_j(trans, path, &jiter); > > > > +err: > > bch2_btree_and_journal_iter_exit(&jiter); > > return ret; > > } > > -- > > 2.47.0 Best regards, Piotr Zalewski
