From e0155cc40781a98d41ae2bb9c46cc4109a6ef8a3 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sat, 16 Jun 2018 20:21:45 -0400 Subject: [PATCH] jbd2: don't mark block as modified if the handle is out of credits 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 Change-Id: Id8501e9b600fb35003f6cb9951cc187c1ad5801f Signed-off-by: Theodore Ts'o [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 Signed-off-by: Kevin F. Haggerty --- 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 436b5369a9f..cf2ffa71a64 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1121,11 +1121,11 @@ 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--; }