Commit 61df0495 authored by Artem Sadovnikov's avatar Artem Sadovnikov Committed by Yongjian Sun
Browse files

ext4: fix i_data_sem unlock order in ext4_ind_migrate() 

mainline inclusion
from mainline-v6.12-rc1
commit cc749e61c011c255d81b192a822db650c68b313f
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYRBL
CVE: CVE-2024-50006

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cc749e61c011c255d81b192a822db650c68b313f



--------------------------------

Fuzzing reports a possible deadlock in jbd2_log_wait_commit.

This issue is triggered when an EXT4_IOC_MIGRATE ioctl is set to require
synchronous updates because the file descriptor is opened with O_SYNC.
This can lead to the jbd2_journal_stop() function calling
jbd2_might_wait_for_commit(), potentially causing a deadlock if the
EXT4_IOC_MIGRATE call races with a write(2) system call.

This problem only arises when CONFIG_PROVE_LOCKING is enabled. In this
case, the jbd2_might_wait_for_commit macro locks jbd2_handle in the
jbd2_journal_stop function while i_data_sem is locked. This triggers
lockdep because the jbd2_journal_start function might also lock the same
jbd2_handle simultaneously.

Found by Linux Verification Center (linuxtesting.org) with syzkaller.

Reviewed-by: default avatarRitesh Harjani (IBM) <ritesh.list@gmail.com>
Co-developed-by: default avatarMikhail Ukhin <mish.uxin2012@yandex.ru>
Signed-off-by: default avatarMikhail Ukhin <mish.uxin2012@yandex.ru>
Signed-off-by: default avatarArtem Sadovnikov <ancowi69@gmail.com>
Rule: add
Link: https://lore.kernel.org/stable/20240404095000.5872-1-mish.uxin2012%40yandex.ru
Link: https://patch.msgid.link/20240829152210.2754-1-ancowi69@gmail.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarYongjian Sun <sunyongjian1@huawei.com>
parent b324fa0a

fs/ext4/migrate.c

+1 −1
Original line number Diff line number Diff line
@@ -663,8 +663,8 @@ int ext4_ind_migrate(struct inode *inode) 
	if (unlikely(ret2 && !ret))

		ret = ret2;

errout:

	ext4_journal_stop(handle);

	up_write(&EXT4_I(inode)->i_data_sem);

	ext4_journal_stop(handle);

out_unlock:

	ext4_writepages_up_write(inode->i_sb, alloc_ctx);

	return ret;