dm array: validate array block headers on read

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array_block_check() validates blocknr and csum and nothing else, while
node_check(), next to it, has bounded the structural fields since both
were written. dm_array_cursor_next() takes its loop bound from the
on-disk nr_entries and element_at() is unguarded pointer arithmetic, so
a count larger than the block holds keeps the cursor in one block while
the index grows past it and the read walks off the dm-bufio buffer --
dm_cache_load_mappings() drives it once per cache block at activation.

Check the header against itself: reject a zero value_size, require
max_entries to equal calc_max_entries() for that value_size and block
size, and require nr_entries to fit. Equality rather than an upper bound,
since a count below the real capacity trips BUG_ON() in fill_ablock() and
trim_ablock(). Metadata dm-array writes satisfies all three.

Fixes: 6513c29f44 ("dm persistent data: add transactional array")
Suggested-by: Ming-Hung Tsai <mtsai@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Reviewed-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

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Bryam Vargas 2026-07-31 17:54:54 -05:00 • committed by Mikulas Patocka

parent 68c5c42567

commit 2965787723

1 changed files with 29 additions and 8 deletions

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drivers/md/persistent-data/dm-array.c

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