net: stmmac: fix TSO DMA API usage causing oops

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix TSO DMA API usage causing oops Commit 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data") moved the assignment of tx_skbuff_dma[]'s members to be later in stmmac_tso_xmit(). The buf (dma cookie) and len stored in this structure are passed to dma_unmap_single() by stmmac_tx_clean(). The DMA API requires that the dma cookie passed to dma_unmap_single() is the same as the value returned from dma_map_single(). However, by moving the assignment later, this is not the case when priv->dma_cap.addr64 > 32 as "des" is offset by proto_hdr_len. This causes problems such as: dwc-eth-dwmac 2490000.ethernet eth0: Tx DMA map failed and with DMA_API_DEBUG enabled: DMA-API: dwc-eth-dwmac 2490000.ethernet: device driver tries to +free DMA memory it has not allocated [device address=0x000000ffffcf65c0] [size=66 bytes] Fix this by maintaining "des" as the original DMA cookie, and use tso_des to pass the offset DMA cookie to stmmac_tso_allocator(). Full details of the crashes can be found at: https://lore.kernel.org/all/d8112193-0386-4e14-b516-37c2d838171a@nvidia.com/ https://lore.kernel.org/all/klkzp5yn5kq5efgtrow6wbvnc46bcqfxs65nz3qy77ujr5turc@bwwhelz2l4dw/

References

• https://git.kernel.org/stable/c/05968b6dd0ffc65d7386608b11a11fb4fdfc9f36
• https://git.kernel.org/stable/c/6abcdc9a73274052a9e96a1926994ecf9aedad82
• https://git.kernel.org/stable/c/db3667c9bbfbbf5de98e6c9542f7e03fb5243286
• https://git.kernel.org/stable/c/9d5dd7ccea1b46a9a7c6b3c2b9e5ed8864e185e2
• https://git.kernel.org/stable/c/4c49f38e20a57f8abaebdf95b369295b153d1f8e