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Subject[PATCH 4.14 15/53] jbd2: dont mark block as modified if the handle is out of credits
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Theodore Ts'o <tytso@mit.edu>

commit e09463f220ca9a1a1ecfda84fcda658f99a1f12a upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/jbd2/transaction.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1366,6 +1366,13 @@ int jbd2_journal_dirty_metadata(handle_t
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);
@@ -1385,11 +1392,11 @@ int jbd2_journal_dirty_metadata(handle_t
* 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--;
}


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