Commit af98b015 authored by Jeongjun Park's avatar Jeongjun Park Committed by Theodore Ts'o
Browse files

jbd2: fix data-race and null-ptr-deref in jbd2_journal_dirty_metadata() 



Since handle->h_transaction may be a NULL pointer, so we should change it
to call is_handle_aborted(handle) first before dereferencing it.

And the following data-race was reported in my fuzzer:

==================================================================
BUG: KCSAN: data-race in jbd2_journal_dirty_metadata / jbd2_journal_dirty_metadata

write to 0xffff888011024104 of 4 bytes by task 10881 on cpu 1:
 jbd2_journal_dirty_metadata+0x2a5/0x770 fs/jbd2/transaction.c:1556
 __ext4_handle_dirty_metadata+0xe7/0x4b0 fs/ext4/ext4_jbd2.c:358
 ext4_do_update_inode fs/ext4/inode.c:5220 [inline]
 ext4_mark_iloc_dirty+0x32c/0xd50 fs/ext4/inode.c:5869
 __ext4_mark_inode_dirty+0xe1/0x450 fs/ext4/inode.c:6074
 ext4_dirty_inode+0x98/0xc0 fs/ext4/inode.c:6103
....

read to 0xffff888011024104 of 4 bytes by task 10880 on cpu 0:
 jbd2_journal_dirty_metadata+0xf2/0x770 fs/jbd2/transaction.c:1512
 __ext4_handle_dirty_metadata+0xe7/0x4b0 fs/ext4/ext4_jbd2.c:358
 ext4_do_update_inode fs/ext4/inode.c:5220 [inline]
 ext4_mark_iloc_dirty+0x32c/0xd50 fs/ext4/inode.c:5869
 __ext4_mark_inode_dirty+0xe1/0x450 fs/ext4/inode.c:6074
 ext4_dirty_inode+0x98/0xc0 fs/ext4/inode.c:6103
....

value changed: 0x00000000 -> 0x00000001
==================================================================

This issue is caused by missing data-race annotation for jh->b_modified.
Therefore, the missing annotation needs to be added.

Reported-by: default avatar <syzbot+de24c3fe3c4091051710@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=de24c3fe3c4091051710


Fixes: 6e06ae88 ("jbd2: speedup jbd2_journal_dirty_metadata()")
Signed-off-by: default avatarJeongjun Park <aha310510@gmail.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250514130855.99010-1-aha310510@gmail.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
parent e80325ef

fs/jbd2/transaction.c

+3 −2
Original line number Diff line number Diff line
@@ -1509,7 +1509,7 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 
				jh->b_next_transaction == transaction);

		spin_unlock(&jh->b_state_lock);

	}

	if (jh->b_modified == 1) {

	if (data_race(jh->b_modified == 1)) {

		/* If it's in our transaction it must be in BJ_Metadata list. */

		if (data_race(jh->b_transaction == transaction &&

		    jh->b_jlist != BJ_Metadata)) {
@@ -1528,7 +1528,6 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 
		goto out;

	}



	journal = transaction->t_journal;

	spin_lock(&jh->b_state_lock);



	if (is_handle_aborted(handle)) {
@@ -1543,6 +1542,8 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 
		goto out_unlock_bh;

	}



	journal = transaction->t_journal;



	if (jh->b_modified == 0) {

		/*

		 * This buffer's got modified and becoming part