drm/panthor: reject firmware sections with oversized data

In the Linux kernel, the following vulnerability has been resolved:

drm/panthor: reject firmware sections with oversized data

In panthor_fw_load_section_entry(), the data size to copy is calculated
without validating it against the allocated section_size:

section->data.size = hdr.data.end - hdr.data.start;

If a crafted firmware sets data.size larger than the allocated memory,
this could cause a heap buffer overflow in panthor_fw_init_section_mem()

memcpy(section->mem->kmap, section->data.buf, section->data.size);

Additionally, if the section->data.size exceeds the BO size, could this
memset underflow the size calculation, leading to a massive out-of-bounds
zeroing of kernel memory?

memset(section->mem->kmap + section->data.size, 0,
panthor_kernel_bo_size(section->mem) - section->data.size);

Reject section entries whose initial data is larger than the section size.