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net: usb: smsc75xx: stop lying about skb->truesize

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

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

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 1e2c611723 ("net: cdc_ncm: reduce skb truesize
in rx path") and 4ce62d5b2f ("net: usb: ax88179_178a:
stop lying about skb->truesize")

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steve Glendinning <steve.glendinning@shawell.net>
Link: https://lore.kernel.org/r/20240506142358.3657918-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-05-06 14:23:58 +00:00 committed by Jakub Kicinski
parent 9aad6e45c4
commit 1b3b2d9e77
1 changed files with 4 additions and 8 deletions
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12
drivers/net/usb/smsc75xx.c
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@ -2234,27 +2234,23 @@ static int smsc75xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
rx_cmd_b); rx_cmd_b);
skb_trim(skb, skb->len - 4); /* remove fcs */ skb_trim(skb, skb->len - 4); /* remove fcs */
skb->truesize = size + sizeof(struct sk_buff);
return 1; return 1;
} }
ax_skb = skb_clone(skb, GFP_ATOMIC); /* Use "size - 4" to remove fcs */
ax_skb = netdev_alloc_skb_ip_align(dev->net, size - 4);
if (unlikely(!ax_skb)) { if (unlikely(!ax_skb)) {
netdev_warn(dev->net, "Error allocating skb\n"); netdev_warn(dev->net, "Error allocating skb\n");
return 0; return 0;
} }
ax_skb->len = size; skb_put(ax_skb, size - 4);
ax_skb->data = packet; memcpy(ax_skb->data, packet, size - 4);
skb_set_tail_pointer(ax_skb, size);
smsc75xx_rx_csum_offload(dev, ax_skb, rx_cmd_a, smsc75xx_rx_csum_offload(dev, ax_skb, rx_cmd_a,
rx_cmd_b); rx_cmd_b);
skb_trim(ax_skb, ax_skb->len - 4); /* remove fcs */
ax_skb->truesize = size + sizeof(struct sk_buff);
usbnet_skb_return(dev, ax_skb); usbnet_skb_return(dev, ax_skb);
} }