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Commit e09463f2 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

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: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
parent 8cdb5240

fs/jbd2/transaction.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -1361,6 +1361,13 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 
		if (jh->b_transaction == transaction &&

		if (jh->b_transaction == transaction &&

		    jh->b_jlist != BJ_Metadata) {

		    jh->b_jlist != BJ_Metadata) {

			jbd_lock_bh_state(bh);

			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 ||

			J_ASSERT_JH(jh, jh->b_transaction != transaction ||

					jh->b_jlist == BJ_Metadata);

					jh->b_jlist == BJ_Metadata);

			jbd_unlock_bh_state(bh);

			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

		 * of the transaction. This needs to be done

		 * once a transaction -bzzz

		 * once a transaction -bzzz

		 */

		 */

		jh->b_modified = 1;

		if (handle->h_buffer_credits <= 0) {

		if (handle->h_buffer_credits <= 0) {

			ret = -ENOSPC;

			ret = -ENOSPC;

			goto out_unlock_bh;

			goto out_unlock_bh;

		}

		}

		jh->b_modified = 1;

		handle->h_buffer_credits--;

		handle->h_buffer_credits--;

	}

	}