Commit b60528d9 authored by Demi Marie Obenour's avatar Demi Marie Obenour Committed by Mike Snitzer
Browse files

dm ioctl: Check dm_target_spec is sufficiently aligned 



Otherwise subsequent code, if given malformed input, could dereference
a misaligned 'struct dm_target_spec *'.

Signed-off-by: default avatarDemi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> # use %zu
Reviewed-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 2971c058

drivers/md/dm-ioctl.c

+9 −0
Original line number Diff line number Diff line
@@ -1394,6 +1394,15 @@ static inline blk_mode_t get_mode(struct dm_ioctl *param) 
static int next_target(struct dm_target_spec *last, uint32_t next, void *end,

		       struct dm_target_spec **spec, char **target_params)

{

	static_assert(__alignof__(struct dm_target_spec) <= 8,

		"struct dm_target_spec must not require more than 8-byte alignment");



	if (next % __alignof__(struct dm_target_spec)) {

		DMERR("Next dm_target_spec (offset %u) is not %zu-byte aligned",

		      next, __alignof__(struct dm_target_spec));

		return -EINVAL;

	}



	*spec = (struct dm_target_spec *) ((unsigned char *) last + next);

	*target_params = (char *) (*spec + 1);