On Sat, 3 Jun 2023, Demi Marie Obenour wrote: > 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@xxxxxxxxxxxxxxxxxxxxxx> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@xxxxxxxxxxxxxxx Reviewed-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > --- > 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, > -- > Sincerely, > Demi Marie Obenour (she/her/hers) > Invisible Things Lab > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/dm-devel > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel