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| author | Demi Marie Obenour <demi@invisiblethingslab.com> | 2023-06-03 16:52:41 +0200 |
|---|---|---|
| committer | Mike Snitzer <snitzer@kernel.org> | 2023-06-23 16:31:51 +0200 |
| commit | 10655c7a48570315343fdd9cc6acb261d57c2c7a (patch) | |
| tree | 737ca49322e11ed9dffdd85ef5f9033f125a4985 | |
| parent | dm ioctl: Avoid pointer arithmetic overflow (diff) | |
| download | linux-10655c7a48570315343fdd9cc6acb261d57c2c7a.tar.xz linux-10655c7a48570315343fdd9cc6acb261d57c2c7a.zip | |
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: Demi Marie Obenour <demi@invisiblethingslab.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to '')
| -rw-r--r-- | drivers/md/dm-ioctl.c | 28 |
1 files changed, 21 insertions, 7 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index e322fd490634..a92abbe90981 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -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, |