accel/qaic: Add overflow check to remap_pfn_range during mmap

accel/qaic: Add overflow check to remap_pfn_range during mmap

The call to remap_pfn_range in qaic_gem_object_mmap is susceptible to
(re)mapping beyond the VMA if the BO is too large. This can cause use
after free issues when munmap() unmaps only the VMA region and not the
additional mappings. To prevent this, check the remaining size of the
VMA before remapping and truncate the remapped length if sg->length is
too large.

Reported-by: Lukas Maar <lukas.maar@tugraz.at>
Fixes: ff13be830333 ("accel/qaic: Add datapath")
Reviewed-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Signed-off-by: Zack McKevitt <zachary.mckevitt@oss.qualcomm.com>
Reviewed-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>
[jhugo: fix braces from checkpatch --strict]
Signed-off-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>
Link: https://patch.msgid.link/20260430193858.1178641-1-zachary.mckevitt@oss.qualcomm.com