From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6212436C9E5 for ; Fri, 24 Apr 2026 14:07:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777039672; cv=none; b=gK/OW3pPlNa1q7QGeKbCsoheRpfwruJqhNKYv4tHC4X+cEycoExEW9LpMoLVnt20kdlE8YIYgLlcAP8LmNSu5DMtmavreYGyFLqm2zT5lApOSfBFk2VhsdbYHyY49GUuHJImFycahpJEOCoT2qT9Okcu5QVMe4ujCrJzzN453C0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777039672; c=relaxed/simple; bh=Qh841olW8uUVP92Wp+5T/qAK89BgsTbRjQ0tHRAW43k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KlYx6NlOt0D7WCCzQXKVhVYT2GWeuheDGGdqRmCvKQr7tpCC125MDgNcc8Qefpfsdt+TBAHtIYGeDohYRiHtCu4h1S35YPPLqMbHu/7NmkO5UFBXpRrnsZkxtkoCAiIizCpnDFqAAqAzGMk6TxUPh7vZ/dah20XCFcazUZLHCp4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GDNSvhqs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GDNSvhqs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F05DC19425; Fri, 24 Apr 2026 14:07:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777039672; bh=Qh841olW8uUVP92Wp+5T/qAK89BgsTbRjQ0tHRAW43k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GDNSvhqsgCaccKUtHKaj+5NGVjdSEHOMVu3ymu1KKFTGTNQrTNj/TGkj11wrV1ymr omEFo/rx0WPZluEbNgQbcOY4mX1IOvymwl/SLEisPa+qpZNvrjr1mRujnW0LPeDTBq msGswoHXD/PqYJ0Huf3n1jhP1FTLy46m0ow9yb/8Px7yDM1HNQeyddQVGMAfbxIhCJ p6ID5Fs2ZCx+C7MISbuh01hrn4OxyOEjwQZwme9j+v6eI6uYq4STcdmhqVqr7Za0xi PsSmZdtKwBcYpIC2xZBZvZK9N9UAgMyQfQO1qPUQgZgGdSzXwOWtQsI7l/OZ7vR1NN dblucHBMgwLrg== From: Sasha Levin To: stable@vger.kernel.org Cc: Yongpeng Yang , stable@kernel.org, syzbot+6e4cb1cac5efc96ea0ca@syzkaller.appspotmail.com, Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 5.10.y] f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io() Date: Fri, 24 Apr 2026 10:07:49 -0400 Message-ID: <20260424140749.2151644-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026042435-dreary-backshift-e993@gregkh> References: <2026042435-dreary-backshift-e993@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Yongpeng Yang [ Upstream commit 2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53 ] The xfstests case "generic/107" and syzbot have both reported a NULL pointer dereference. The concurrent scenario that triggers the panic is as follows: F2FS_WB_CP_DATA write callback umount - f2fs_write_checkpoint - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA) - blk_mq_end_request - bio_endio - f2fs_write_end_io : dec_page_count(sbi, F2FS_WB_CP_DATA) : wake_up(&sbi->cp_wait) - kill_f2fs_super - kill_block_super - f2fs_put_super : iput(sbi->node_inode) : sbi->node_inode = NULL : f2fs_in_warm_node_list - is_node_folio // sbi->node_inode is NULL and panic The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is decremented to zero. As a result, f2fs_in_warm_node_list() may dereference a NULL node_inode when checking whether a folio belongs to the node inode, leading to a panic. This patch fixes the issue by calling f2fs_in_warm_node_list() before decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the use-after-free condition. Cc: stable@kernel.org Fixes: 50fa53eccf9f ("f2fs: fix to avoid broken of dnode block list") Reported-by: syzbot+6e4cb1cac5efc96ea0ca@syzkaller.appspotmail.com Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim [ folio => page ] Signed-off-by: Sasha Levin --- fs/f2fs/data.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 35be155a284eb..52b20b9165b68 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -377,6 +377,8 @@ static void f2fs_write_end_io(struct bio *bio) f2fs_bug_on(sbi, page->mapping == NODE_MAPPING(sbi) && page->index != nid_of_node(page)); + if (f2fs_in_warm_node_list(sbi, page)) + f2fs_del_fsync_node_entry(sbi, page); dec_page_count(sbi, type); @@ -388,8 +390,6 @@ static void f2fs_write_end_io(struct bio *bio) wq_has_sleeper(&sbi->cp_wait)) wake_up(&sbi->cp_wait); - if (f2fs_in_warm_node_list(sbi, page)) - f2fs_del_fsync_node_entry(sbi, page); clear_cold_data(page); end_page_writeback(page); } -- 2.53.0