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 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org --- drivers/md/dm-ioctl.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 64e8f16d344c47057de5e2d29e3d63202197dca0..da6ca26b51d0953df380582bb3a51c2ec22c27cb 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1391,7 +1391,7 @@ static inline fmode_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, @@ -1404,7 +1404,7 @@ 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 @@ -1423,10 +1423,7 @@ 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, @@ -1436,8 +1433,9 @@ 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__); @@ -1445,6 +1443,13 @@ 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) { @@ -1452,6 +1457,15 @@ 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,