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 3DBB81B424F; Sun, 7 Sep 2025 20:21:18 +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=1757276478; cv=none; b=jhfQT3uSDIp4QFjAWgYnYfDF6Afob245E1hDxkS9YM248X9rHdvI12om7w/HgLR+x6gnm/ByTxK1D5RJ/zUnI81e26mgDGvg5xj92PJMwdNLd47kG9cRRddTfLLol6Ko2SPzHexHx3ROTzN7iiOphNB+ykrtgDCXfDxubOJJHfw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757276478; c=relaxed/simple; bh=uPHazi7ST8e3CWC1XephXK9MNwarKgbkjR4XVX1FtLA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=d6x/xz15wB1gAcCgQhO/anaU+9Is1vFbB9PRZIqtEO9aNd7g8TEKs9FV23RWWIqQnqUEXN5ktZOcfI6kVpVcA75TPC0wTnmU1zHvA4QENM+IygbE78ITZD/6XV06h9TUkLg5aGip/UMhFcdZT1ol3bl03Ck1Pa2E3aKKOD5CGBo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fcXWOlAC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fcXWOlAC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ABBEAC4CEF0; Sun, 7 Sep 2025 20:21:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1757276478; bh=uPHazi7ST8e3CWC1XephXK9MNwarKgbkjR4XVX1FtLA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fcXWOlACCkz7eRmUQQ16EnxqHaUfF8lAdkkwipe8owxSOvQLR5SIxQlh6EjT6qfnp Ni4Cer2lKT8bFICxGiCr45k3a5m4ygCx+58FNcCd26tqYhTE7ZXQJvy7y1QlEFrWSH 6il1govARyUQDGXh/UtVrPPxTv7WVSxrOr7gqbb8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jiufei Xue , Jan Kara , Christian Brauner , Sasha Levin Subject: [PATCH 6.6 013/121] fs: writeback: fix use-after-free in __mark_inode_dirty() Date: Sun, 7 Sep 2025 21:57:29 +0200 Message-ID: <20250907195610.153427506@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250907195609.817339617@linuxfoundation.org> References: <20250907195609.817339617@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiufei Xue [ Upstream commit d02d2c98d25793902f65803ab853b592c7a96b29 ] An use-after-free issue occurred when __mark_inode_dirty() get the bdi_writeback that was in the progress of switching. CPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1 ...... pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __mark_inode_dirty+0x124/0x418 lr : __mark_inode_dirty+0x118/0x418 sp : ffffffc08c9dbbc0 ........ Call trace: __mark_inode_dirty+0x124/0x418 generic_update_time+0x4c/0x60 file_modified+0xcc/0xd0 ext4_buffered_write_iter+0x58/0x124 ext4_file_write_iter+0x54/0x704 vfs_write+0x1c0/0x308 ksys_write+0x74/0x10c __arm64_sys_write+0x1c/0x28 invoke_syscall+0x48/0x114 el0_svc_common.constprop.0+0xc0/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x40/0xe4 el0t_64_sync_handler+0x120/0x12c el0t_64_sync+0x194/0x198 Root cause is: systemd-random-seed kworker ---------------------------------------------------------------------- ___mark_inode_dirty inode_switch_wbs_work_fn spin_lock(&inode->i_lock); inode_attach_wb locked_inode_to_wb_and_lock_list get inode->i_wb spin_unlock(&inode->i_lock); spin_lock(&wb->list_lock) spin_lock(&inode->i_lock) inode_io_list_move_locked spin_unlock(&wb->list_lock) spin_unlock(&inode->i_lock) spin_lock(&old_wb->list_lock) inode_do_switch_wbs spin_lock(&inode->i_lock) inode->i_wb = new_wb spin_unlock(&inode->i_lock) spin_unlock(&old_wb->list_lock) wb_put_many(old_wb, nr_switched) cgwb_release old wb released wb_wakeup_delayed() accesses wb, then trigger the use-after-free issue Fix this race condition by holding inode spinlock until wb_wakeup_delayed() finished. Signed-off-by: Jiufei Xue Link: https://lore.kernel.org/20250728100715.3863241-1-jiufei.xue@samsung.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/fs-writeback.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 0a498bc60f557..ed110568d6127 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -2536,10 +2536,6 @@ void __mark_inode_dirty(struct inode *inode, int flags) wakeup_bdi = inode_io_list_move_locked(inode, wb, dirty_list); - spin_unlock(&wb->list_lock); - spin_unlock(&inode->i_lock); - trace_writeback_dirty_inode_enqueue(inode); - /* * If this is the first dirty inode for this bdi, * we have to wake-up the corresponding bdi thread @@ -2549,6 +2545,11 @@ void __mark_inode_dirty(struct inode *inode, int flags) if (wakeup_bdi && (wb->bdi->capabilities & BDI_CAP_WRITEBACK)) wb_wakeup_delayed(wb); + + spin_unlock(&wb->list_lock); + spin_unlock(&inode->i_lock); + trace_writeback_dirty_inode_enqueue(inode); + return; } } -- 2.50.1