[PATCH v2 54/63] dm integrity: Use struct_group() to zero struct journal_sector

Kees Cook
2021-08-18T06:25:39Z

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Add struct_group() to mark region of struct journal_sector that should be
initialized to zero.

Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/md/dm-integrity.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 40f8116c8e44..59deea0dd305 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -119,8 +119,10 @@ struct journal_entry {
#define JOURNAL_MAC_SIZE (JOURNAL_MAC_PER_SECTOR * JOURNAL_BLOCK_SECTORS)

struct journal_sector {
- __u8 entries[JOURNAL_SECTOR_DATA - JOURNAL_MAC_PER_SECTOR];
- __u8 mac[JOURNAL_MAC_PER_SECTOR];
+ struct_group(sectors,
+ __u8 entries[JOURNAL_SECTOR_DATA - JOURNAL_MAC_PER_SECTOR];
+ __u8 mac[JOURNAL_MAC_PER_SECTOR];
+ );
commit_id_t commit_id;
};

@@ -2856,7 +2858,8 @@ static void init_journal(struct dm_integrity_c *ic, unsigned start_section,
wraparound_section(ic, &i);
for (j = 0; j < ic->journal_section_sectors; j++) {
struct journal_sector *js = access_journal(ic, i, j);
- memset(&js->entries, 0, JOURNAL_SECTOR_DATA);
+ BUILD_BUG_ON(sizeof(js->sectors) != JOURNAL_SECTOR_DATA);
+ memset(&js->sectors, 0, sizeof(js->sectors));
js->commit_id = dm_integrity_commit_id(ic, i, j, commit_seq);
}
for (j = 0; j < ic->journal_section_entries; j++) {
--
2.30.2