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Message-ID: <20241026174155.233430-3-pZ010001011111@proton.me>
Date: Sat, 26 Oct 2024 17:46:33 +0000
From: Piotr Zalewski <pZ010001011111@...ton.me>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: skhan@...uxfoundation.org, Piotr Zalewski <pZ010001011111@...ton.me>, syzbot+005ef9aa519f30d97657@...kaller.appspotmail.com, Alan Huang <mmpgouride@...il.com>
Subject: [PATCH v2] 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 error message with position at
which node wasn't found and its parent node information. Call
bch2_topology_error and return error code returned by it to ensure that
topology error is handled properly.
Reported-by: syzbot+005ef9aa519f30d97657@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=005ef9aa519f30d97657
Fixes: 5222a4607cd8 ("bcachefs: BTREE_ITER_WITH_JOURNAL")
Suggested-by: Alan Huang <mmpgouride@...il.com>
Suggested-by: Kent Overstreet <kent.overstreet@...ux.dev>
Signed-off-by: Piotr Zalewski <pZ010001011111@...ton.me>
---
Notes:
changes in v2:
- make commit message more verbose.
- set topology error, print error message and return
appropriate error code.
link to v1: https://lore.kernel.org/linux-bcachefs/20241023072024.98915-3-pZ010001011111@proton.me/
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 15ac72b1af51..40c824779b15 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -880,6 +880,18 @@ 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, " within parent node ");
+ bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&l->b->key));
+
+ ret = bch2_fs_topology_error(c, "%s", buf.buf);
+ printbuf_exit(&buf);
+ goto err;
+ }
bch2_bkey_buf_reassemble(out, c, k);
@@ -887,6 +899,7 @@ 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
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