From 3726a1970bd72419aa7a54f574635f855b98d67a Mon Sep 17 00:00:00 2001 From: Piotr Zalewski Date: Sun, 27 Oct 2024 19:46:52 +0000 Subject: [PATCH] bcachefs: Fix NULL ptr dereference in btree_node_iter_and_journal_peek 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. When key returned from bch2_btree_and_journal_iter_peek is NULL it means that btree topology needs repair. Print topology error message with position at which node wasn't found, its parent node information and btree_id with level. Return error code returned by bch2_topology_error to ensure that topology error is handled properly by recovery. Reported-by: syzbot+005ef9aa519f30d97657@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=005ef9aa519f30d97657 Fixes: 5222a4607cd8 ("bcachefs: BTREE_ITER_WITH_JOURNAL") Suggested-by: Alan Huang Suggested-by: Kent Overstreet Signed-off-by: Piotr Zalewski Signed-off-by: Kent Overstreet --- fs/bcachefs/btree_iter.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c index 0883cf6e1a3e..eef9b89c561d 100644 --- a/fs/bcachefs/btree_iter.c +++ b/fs/bcachefs/btree_iter.c @@ -882,6 +882,18 @@ 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) { + struct printbuf buf = PRINTBUF; + + prt_str(&buf, "node not found at pos "); + bch2_bpos_to_text(&buf, path->pos); + prt_str(&buf, " at btree "); + bch2_btree_pos_to_text(&buf, c, l->b); + + ret = bch2_fs_topology_error(c, "%s", buf.buf); + printbuf_exit(&buf); + goto err; + } bch2_bkey_buf_reassemble(out, c, k); @@ -889,6 +901,7 @@ 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; }