Patch "sfc: fix null pointer dereference in efx_hard_start_xmit" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    sfc: fix null pointer dereference in efx_hard_start_xmit

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     sfc-fix-null-pointer-dereference-in-efx_hard_start_x.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9edb49a818940566c077c09e57d166af97642fbe
Author: Íñigo Huguet <ihuguet@xxxxxxxxxx>
Date:   Wed Sep 14 13:11:35 2022 +0200

    sfc: fix null pointer dereference in efx_hard_start_xmit
    
    [ Upstream commit 0a242eb2913a4aa3d6fbdb86559f27628e9466f3 ]
    
    Trying to get the channel from the tx_queue variable here is wrong
    because we can only be here if tx_queue is NULL, so we shouldn't
    dereference it. As the above comment in the code says, this is very
    unlikely to happen, but it's wrong anyway so let's fix it.
    
    I hit this issue because of a different bug that caused tx_queue to be
    NULL. If that happens, this is the error message that we get here:
      BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
      [...]
      RIP: 0010:efx_hard_start_xmit+0x153/0x170 [sfc]
    
    Fixes: 12804793b17c ("sfc: decouple TXQ type from label")
    Reported-by: Tianhao Zhao <tizhao@xxxxxxxxxx>
    Signed-off-by: Íñigo Huguet <ihuguet@xxxxxxxxxx>
    Acked-by: Edward Cree <ecree.xilinx@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20220914111135.21038-1-ihuguet@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 1665529a7271..fcc7de8ae2bf 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -545,7 +545,7 @@ netdev_tx_t efx_hard_start_xmit(struct sk_buff *skb,
 		 * previous packets out.
 		 */
 		if (!netdev_xmit_more())
-			efx_tx_send_pending(tx_queue->channel);
+			efx_tx_send_pending(efx_get_tx_channel(efx, index));
 		return NETDEV_TX_OK;
 	}