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jbd2: don't mark block as modified if the handle is out of credits 

Do not set the b_modified flag in block's journal head should not
until after we're sure that jbd2_journal_dirty_metadat() will not
abort with an error due to there not being enough space reserved in
the jbd2 handle.

Otherwise, future attempts to modify the buffer may lead a large
number of spurious errors and warnings.

This addresses CVE-2018-10883.

https://bugzilla.kernel.org/show_bug.cgi?id=200071

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
This commit is contained in:
Theodore Ts'o 2018-06-16 20:21:45 -04:00
parent 8cdb5240ec
commit e09463f220
1 changed files with 8 additions and 1 deletions
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9
fs/jbd2/transaction.c
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@ -1361,6 +1361,13 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
if (jh->b_transaction == transaction &&
jh->b_jlist != BJ_Metadata) {
jbd_lock_bh_state(bh);
if (jh->b_transaction == transaction &&
jh->b_jlist != BJ_Metadata)
pr_err("JBD2: assertion failure: h_type=%u "
"h_line_no=%u block_no=%llu jlist=%u\n",
handle->h_type, handle->h_line_no,
(unsigned long long) bh->b_blocknr,
jh->b_jlist);
J_ASSERT_JH(jh, jh->b_transaction != transaction ||
jh->b_jlist == BJ_Metadata);
jbd_unlock_bh_state(bh);
@ -1380,11 +1387,11 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
* of the transaction. This needs to be done
* once a transaction -bzzz
*/
jh->b_modified = 1;
if (handle->h_buffer_credits <= 0) {
ret = -ENOSPC;
goto out_unlock_bh;
}
jh->b_modified = 1;
handle->h_buffer_credits--;
}