3.16.58-rc1 review patch. If anyone has any objections, please let me know.
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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 [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@decadent.org.uk --- --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1288,11 +1288,11 @@ 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--; }