libnvdimm/labels: Prevent integer overflow in __nd_label_validate()

The on-media namespace index field nslot is a u32 read from the DIMM
label storage area.  __nd_label_validate() bounds it against the config
area size, but sizeof_namespace_label() returns unsigned, so the product
nslot * label_size is evaluated in 32-bit and wraps modulo 2^32 before
the comparison.  A crafted nslot passes the bound and is then used as the
loop trip count in nd_label_data_init(), whose memset() walks off the end
of the config_size buffer: an out-of-bounds write.

The field is not trusted -- it comes from the medium, or from userspace
via ND_CMD_SET_CONFIG_DATA.  Evaluate the product in 64-bit so the bound
check is exact; conforming labels are unaffected.

The check was safe when introduced by commit 4a826c83db4e ("libnvdimm:
namespace indices: read and validate"): it multiplied by sizeof(struct
nd_namespace_label), a size_t, so on a 64-bit build the product did not
wrap.  Commit 564e871aa66f ("libnvdimm, label: add v1.2 nvdimm label
definitions") narrowed it to 32 bits when the label size became a runtime
value read via sizeof_namespace_label().

Fixes: 564e871aa66f ("libnvdimm, label: add v1.2 nvdimm label definitions")
Cc: stable@vger.kernel.org
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Link: https://patch.msgid.link/20260624-b4-disp-d8279485-v3-1-cdb6cab28b41@proton.me
Signed-off-by: Alison Schofield <alison.schofield@intel.com>

0 files changed, 0 insertions, 0 deletions