CVE-2026-98242dma-buf: Fix silent overflow for phys vec to sgt

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/6b98fd7106d4e486f432664893dcd4d6fa3a9693
• https://git.kernel.org/stable/c/b344ca94e8cc85796f16ea25e2e5a8e0303fe813