net: usb: ax88179_178a: stop lying about skb->truesize

Some usb drivers try to set small skb->truesize and break
core networking stacks.

In this patch, I removed one of the skb->truesize overide.

I also replaced one skb_clone() by an allocation of a fresh
and small skb, to get minimally sized skbs, like we did
in commit 1e2c61172342 ("net: cdc_ncm: reduce skb truesize
in rx path")

Fixes: f8ebb3ac881b ("net: usb: ax88179_178a: Fix packet receiving")
Reported-by: shironeko <shironeko@tesaguri.club>
Closes: https://lore.kernel.org/netdev/c110f41a0d2776b525930f213ca9715c@tesaguri.club/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jose Alonso <joalonsof@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240421193828.1966195-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/usb/ax88179_178a.c b/drivers/net/usb/ax88179_178a.c
index 752f821a19901f313a1aca51fe332539ce82385b..df9d767cb524241848c744504d6e2999efc42ed5 100644 (file)
--- a/drivers/net/usb/ax88179_178a.c
+++ b/drivers/net/usb/ax88179_178a.c
@@ -1456,21 +1456,16 @@ static int ax88179_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
                        /* Skip IP alignment pseudo header */
                        skb_pull(skb, 2);
 
-                       skb->truesize = SKB_TRUESIZE(pkt_len_plus_padd);
                        ax88179_rx_checksum(skb, pkt_hdr);
                        return 1;
                }
 
-               ax_skb = skb_clone(skb, GFP_ATOMIC);
+               ax_skb = netdev_alloc_skb_ip_align(dev->net, pkt_len);
                if (!ax_skb)
                        return 0;
-               skb_trim(ax_skb, pkt_len);
+               skb_put(ax_skb, pkt_len);
+               memcpy(ax_skb->data, skb->data + 2, pkt_len);
 
-               /* Skip IP alignment pseudo header */
-               skb_pull(ax_skb, 2);
-
-               skb->truesize = pkt_len_plus_padd +
-                               SKB_DATA_ALIGN(sizeof(struct sk_buff));
                ax88179_rx_checksum(ax_skb, pkt_hdr);
                usbnet_skb_return(dev, ax_skb);