libnvdimm/labels: Bound the on-media label size before the shift

For a v1.2+ index, __nd_label_validate() computes the label size as
1 << (7 + nsindex[i]->labelsize), where labelsize is a u8 read from
the label storage medium.  A value of 25 or more makes the shift count
reach or exceed the width of int -- undefined behavior -- and 24 already
shifts into the sign bit.  Only 0 (128-byte) and 1 (256-byte) are valid.

Reject a labelsize above 1 before the shift.  The result was rejected by
the following size comparison anyway, so this only removes the undefined
shift on a crafted or corrupted medium; conforming labels are unaffected.

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

0 files changed, 0 insertions, 0 deletions