net: usb: lan78xx: limit size of local TSO packets

BugLink: https://bugs.launchpad.net/bugs/1862429
[ Upstream commit f8d7408a4d7f60f8b2df0f81decdc882dd9c20dc ]

lan78xx_tx_bh() makes sure to not exceed MAX_SINGLE_PACKET_SIZE
bytes in the aggregated packets it builds, but does
nothing to prevent large GSO packets being submitted.

Pierre-Francois reported various hangs when/if TSO is enabled.

For localy generated packets, we can use netif_set_gso_max_size()
to limit the size of TSO packets.

Note that forwarded packets could still hit the issue,
so a complete fix might require implementing .ndo_features_check
for this driver, forcing a software segmentation if the size
of the TSO packet exceeds MAX_SINGLE_PACKET_SIZE.

Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: RENARD Pierre-Francois <pfrenard@gmail.com>
Tested-by: RENARD Pierre-Francois <pfrenard@gmail.com>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Woojung Huh <woojung.huh@microchip.com>
Cc: Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 2999cae8654efe01b35e7d545843cc20e9feae04..7dacffd9858620cfbdd85800ff49942c5e87cdb1 100644 (file)
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -3757,6 +3757,7 @@ static int lan78xx_probe(struct usb_interface *intf,
 
        /* MTU range: 68 - 9000 */
        netdev->max_mtu = MAX_SINGLE_PACKET_SIZE;
+       netif_set_gso_max_size(netdev, MAX_SINGLE_PACKET_SIZE - MAX_HEADER);
 
        dev->ep_blkin = (intf->cur_altsetting)->endpoint + 0;
        dev->ep_blkout = (intf->cur_altsetting)->endpoint + 1;