From b60528d9e68113e2c297c3a45102332cb1d3e608 Mon Sep 17 00:00:00 2001
From: Demi Marie Obenour <demi@invisiblethingslab.com>
Date: Sat, 3 Jun 2023 10:52:39 -0400
Subject: [PATCH] dm ioctl: Check dm_target_spec is sufficiently aligned
Git-commit: b60528d9e68113e2c297c3a45102332cb1d3e608
Patch-mainline: v6.5-rc1
References: jsc#PED-7514
Otherwise subsequent code, if given malformed input, could dereference
a misaligned 'struct dm_target_spec *'.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> # use %zu
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/dm-ioctl.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 8ba4cbb92351..3a6989b7817d 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -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);
--
2.35.3