> Subject: [PATCH net] net: mana: Fix RX buf alloc_size alignment and atomic op
> panic
>
> The MANA driver's RX buffer alloc_size is passed into napi_build_skb() to create
> SKB. skb_shinfo(skb) is located at the end of skb, and its alignment is affected by
> the alloc_size passed into napi_build_skb(). The size needs to be aligned properly
> for better performance and atomic operations.
> Otherwise, on ARM64 CPU, for certain MTU settings like 4000, atomic operations
> may panic on the skb_shinfo(skb)->dataref due to alignment fault.
>
> To fix this bug, add proper alignment to the alloc_size calculation.
>
> Sample panic info:
> [ 253.298819] Unable to handle kernel paging request at virtual address
> ffff000129ba5cce [ 253.300900] Mem abort info:
> [ 253.301760] ESR = 0x0000000096000021
> [ 253.302825] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 253.304268] SET = 0, FnV = 0
> [ 253.305172] EA = 0, S1PTW = 0
> [ 253.306103] FSC = 0x21: alignment fault
> Call trace:
> __skb_clone+0xfc/0x198
> skb_clone+0x78/0xe0
> raw6_local_deliver+0xfc/0x228
> ip6_protocol_deliver_rcu+0x80/0x500
> ip6_input_finish+0x48/0x80
> ip6_input+0x48/0xc0
> ip6_sublist_rcv_finish+0x50/0x78
> ip6_sublist_rcv+0x1cc/0x2b8
> ipv6_list_rcv+0x100/0x150
> __netif_receive_skb_list_core+0x180/0x220
> netif_receive_skb_list_internal+0x198/0x2a8
> __napi_poll+0x138/0x250
> net_rx_action+0x148/0x330
> handle_softirqs+0x12c/0x3a0
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 80f6215b450e ("net: mana: Add support for jumbo frame")
> Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Reviewed-by: Long Li <longli@xxxxxxxxxxxxx>
> ---
> drivers/net/ethernet/microsoft/mana/mana_en.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
> b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index d2f07e179e86..ae717d06e66f 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -599,7 +599,11 @@ static void mana_get_rxbuf_cfg(int mtu, u32 *datasize,
> u32 *alloc_size,
> else
> *headroom = XDP_PACKET_HEADROOM;
>
> - *alloc_size = mtu + MANA_RXBUF_PAD + *headroom;
> + *alloc_size = SKB_DATA_ALIGN(mtu + MANA_RXBUF_PAD + *headroom);
> +
> + /* Using page pool in this case, so alloc_size is PAGE_SIZE */
> + if (*alloc_size < PAGE_SIZE)
> + *alloc_size = PAGE_SIZE;
>
> *datasize = mtu + ETH_HLEN;
> }
> --
> 2.34.1
