Otherwise subsequent code will dereference a misaligned `struct dm_target_spec *`, which is undefined behavior.

Signed-off-by: Demi Marie Obenour demi@invisiblethingslab.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org --- drivers/md/dm-ioctl.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index cc77cf3d410921432eb0c62cdede7d55b9aa674a..34fa74c6a70db8aa67aaba3f6a2fc4f38ef736bc 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1394,6 +1394,13 @@ static inline fmode_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 has excessive alignment requirements"); + if (next % 8) { + DMERR("Next target spec (offset %u) is not 8-byte aligned", next); + return -EINVAL; + } + *spec = (struct dm_target_spec *) ((unsigned char *) last + next); *target_params = (char *) (*spec + 1);