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dm ioctl: structs and parameter strings must not overlap

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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: Demi Marie Obenour <demi@invisiblethingslab.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Demi Marie Obenour 2023-06-03 10:52:41 -04:00 committed by Mike Snitzer
parent 13f4a697f8
commit 10655c7a48
1 changed files with 21 additions and 7 deletions
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28
drivers/md/dm-ioctl.c
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@ -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,