Re: [PATCH 5.4.y] jbd2: fix data-race and null-ptr-deref in jbd2_journal_dirty_metadata()

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: af98b0157adf6504fade79b3e6cb260c4ff68e37

Status in newer kernel trees:
6.15.y | Present (different SHA1: ddfb8877c6b5)
6.12.y | Present (different SHA1: 25cc031107f4)
6.6.y | Present (different SHA1: 543c9aed6f73)
6.1.y | Present (different SHA1: e7c29c3b1d88)
5.15.y | Present (different SHA1: b58688929dc8)
5.10.y | Present (different SHA1: b5960460d84e)

Note: The patch differs from the upstream commit:
---
1:  af98b0157adf6 ! 1:  e2e4e77718de3 jbd2: fix data-race and null-ptr-deref in jbd2_journal_dirty_metadata()
    @@ Metadata
      ## Commit message ##
         jbd2: fix data-race and null-ptr-deref in jbd2_journal_dirty_metadata()
     
    +    commit af98b0157adf6504fade79b3e6cb260c4ff68e37 upstream.
    +
         Since handle->h_transaction may be a NULL pointer, so we should change it
         to call is_handle_aborted(handle) first before dereferencing it.
     
    @@ Commit message
         Cc: stable@kernel.org
     
      ## fs/jbd2/transaction.c ##
    -@@ fs/jbd2/transaction.c: 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)) {
     @@ fs/jbd2/transaction.c: int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
      		goto out;
      	}
      
     -	journal = transaction->t_journal;
    - 	spin_lock(&jh->b_state_lock);
    + 	jbd_lock_bh_state(bh);
      
      	if (is_handle_aborted(handle)) {
     @@ fs/jbd2/transaction.c: int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.4.y        |  Success    |  Success   |