CVE-2026-98242

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

dma-buf: Fix silent overflow for phys vec to sgt

In case MMIO size is bigger than 4G and peer2peer DMA goes
through host bridge, we trigger a code path that assigns the
total linked IOVA (which is greater than 4G) to mapped_len.

Previously, `mapped_len` was declared as 32-bit `unsigned int`.
When accumulating `size_t` lengths, this leads to a silent wrap-around.
This truncation causes truncated lengths to be passed to functions
like `fill_sg_entry()`.

Fix this by changing `mapped_len` to `size_t` (64-bit). While
at it, fix similar potential overflow issues in `calc_sg_nents`
by using `check_add_overflow()` for `nents` and using
`unsigned int` for the loop iterator in `fill_sg_entry` to match.