From: Theodore Ts'o <tytso@xxxxxxx> 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@xxxxxxx> [bwh: Backported to 3.16: Drop the added logging statement, as it's on a code path that doesn't exist here] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> Signed-off-by: Greg Hackmann <ghackmann@xxxxxxxxxx> --- fs/jbd2/transaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index f3818e7cfa60..ab034f48ffe4 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1283,11 +1283,11 @@ 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--; } -- 2.19.0.605.g01d371f741-goog
