CVE-2026-64124 — net: devmem: reject dma-buf bind with non-page-aligned size or SG length

Affected: Linux

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

net: devmem: reject dma-buf bind with non-page-aligned size or SG length

net_devmem_bind_dmabuf() trusts dmabuf->size and sg_dma_len() to be PAGE_SIZE multiples without checking:

- tx_vec is sized dmabuf->size / PAGE_SIZE, and net_devmem_get_niov_at() only bounds-checks virt_addr < dmabuf->size before indexing tx_vec[virt_addr / PAGE_SIZE]. With size = N*PAGE_SIZE + r (1 <= r < PAGE_SIZE), sendmsg() at iov_base = N*PAGE_SIZE passes the bound check and reads tx_vec[N] -- one past.

- owner->area.num_niovs = len / PAGE_SIZE while gen_pool_add_owner() covers the full byte len, so a non-page-multiple non-final sg desyncs num_niovs from the gen_pool region for every later sg, on both RX and TX.

dma-buf does not require page-aligned sizes, so the bind path has to enforce what its own indexing assumes. Reject both with -EINVAL.

The size check is TX-only (only tx_vec is sized off dmabuf->size); the SG-length check covers both directions.

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CVE-2026-64124 — net: devmem: reject dma-buf bind with non-page-aligned size or SG length