net: devmem: decode DMA addresses for TX

Browse source

On 32-bit architectures where dma_addr_t is wider than unsigned long,
page_pool_set_dma_addr_netmem() stores page-aligned DMA addresses shifted
by PAGE_SHIFT. The net_iov branch of __skb_frag_dma_map() adds byte offsets
to the encoded value, so the NIC is programmed with an invalid DMA address.
This can trigger an IOMMU fault or DMA from unintended memory.

Consolidate DMA address encoding, decoding, and representability checks in
netmem helpers. Use the common decoder from the page pool and net_iov TX
paths so both interpret stored addresses consistently.

Reviewed-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20260925201522.254717-4-sdf@fomichev.me
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

...

This commit is contained in:

Stanislav Fomichev 2026-09-25 13:15:22 -07:00 • committed by Paolo Abeni

parent 5bdeb89ec5

commit 5c729e6c71

4 changed files with 35 additions and 23 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

7

include/linux/skbuff.h

View file

27

include/net/netmem.h

View file

10

include/net/page_pool/helpers.h

View file

14

net/core/page_pool_priv.h

View file