Commit 10655c7a authored by Demi Marie Obenour's avatar Demi Marie Obenour Committed by Mike Snitzer
Browse files

dm ioctl: structs and parameter strings must not overlap 



The NUL terminator for each target parameter string must precede the
following 'struct dm_target_spec'.  Otherwise, dm_split_args() might
corrupt this struct.  Furthermore, the first 'struct dm_target_spec'
must come after the 'struct dm_ioctl', as if it overlaps too much
dm_split_args() could corrupt the 'struct dm_ioctl'.

Signed-off-by: default avatarDemi Marie Obenour <demi@invisiblethingslab.com>
Reviewed-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 13f4a697

drivers/md/dm-ioctl.c

+21 −7
Original line number Diff line number Diff line
@@ -1391,7 +1391,7 @@ static inline blk_mode_t get_mode(struct dm_ioctl *param) 
	return mode;

}



static int next_target(struct dm_target_spec *last, uint32_t next, void *end,

static int next_target(struct dm_target_spec *last, uint32_t next, const char *end,

		       struct dm_target_spec **spec, char **target_params)

{

	static_assert(__alignof__(struct dm_target_spec) <= 8,
@@ -1402,7 +1402,7 @@ static int next_target(struct dm_target_spec *last, uint32_t next, void *end, 
	 * sizeof(struct dm_target_spec) or more, as otherwise *last was

	 * out of bounds already.

	 */

	size_t remaining = (char *)end - (char *)last;

	size_t remaining = end - (char *)last;



	/*

	 * There must be room for both the next target spec and the
@@ -1422,10 +1422,7 @@ static int next_target(struct dm_target_spec *last, uint32_t next, void *end, 
	*spec = (struct dm_target_spec *) ((unsigned char *) last + next);

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



	if (*spec < (last + 1))

		return -EINVAL;



	return invalid_str(*target_params, end);

	return 0;

}



static int populate_table(struct dm_table *table,
@@ -1435,8 +1432,9 @@ static int populate_table(struct dm_table *table, 
	unsigned int i = 0;

	struct dm_target_spec *spec = (struct dm_target_spec *) param;

	uint32_t next = param->data_start;

	void *end = (void *) param + param_size;

	const char *const end = (const char *) param + param_size;

	char *target_params;

	size_t min_size = sizeof(struct dm_ioctl);



	if (!param->target_count) {

		DMERR("%s: no targets specified", __func__);
@@ -1444,6 +1442,13 @@ static int populate_table(struct dm_table *table, 
	}



	for (i = 0; i < param->target_count; i++) {

		const char *nul_terminator;



		if (next < min_size) {

			DMERR("%s: next target spec (offset %u) overlaps %s",

			      __func__, next, i ? "previous target" : "'struct dm_ioctl'");

			return -EINVAL;

		}



		r = next_target(spec, next, end, &spec, &target_params);

		if (r) {
@@ -1451,6 +1456,15 @@ static int populate_table(struct dm_table *table, 
			return r;

		}



		nul_terminator = memchr(target_params, 0, (size_t)(end - target_params));

		if (nul_terminator == NULL) {

			DMERR("%s: target parameters not NUL-terminated", __func__);

			return -EINVAL;

		}



		/* Add 1 for NUL terminator */

		min_size = (size_t)(nul_terminator - (const char *)spec) + 1;



		r = dm_table_add_target(table, spec->target_type,

					(sector_t) spec->sector_start,

					(sector_t) spec->length,