Patch "liquidio: Adjust a NULL pointer handling path in lio_vf_rep_copy_packet" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    liquidio: Adjust a NULL pointer handling path in lio_vf_rep_copy_packet

to the 4.19-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:
     liquidio-adjust-a-null-pointer-handling-path-in-lio_.patch
and it can be found in the queue-4.19 subdirectory.

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



commit 6b4cd141f51b3d15c5f296d8deea6a8ba28e749f
Author: Aleksandr Mishin <amishin@xxxxxxxxxx>
Date:   Wed Jun 5 13:11:35 2024 +0300

    liquidio: Adjust a NULL pointer handling path in lio_vf_rep_copy_packet
    
    [ Upstream commit c44711b78608c98a3e6b49ce91678cd0917d5349 ]
    
    In lio_vf_rep_copy_packet() pg_info->page is compared to a NULL value,
    but then it is unconditionally passed to skb_add_rx_frag() which looks
    strange and could lead to null pointer dereference.
    
    lio_vf_rep_copy_packet() call trace looks like:
            octeon_droq_process_packets
             octeon_droq_fast_process_packets
              octeon_droq_dispatch_pkt
               octeon_create_recv_info
                ...search in the dispatch_list...
                 ->disp_fn(rdisp->rinfo, ...)
                  lio_vf_rep_pkt_recv(struct octeon_recv_info *recv_info, ...)
    In this path there is no code which sets pg_info->page to NULL.
    So this check looks unneeded and doesn't solve potential problem.
    But I guess the author had reason to add a check and I have no such card
    and can't do real test.
    In addition, the code in the function liquidio_push_packet() in
    liquidio/lio_core.c does exactly the same.
    
    Based on this, I consider the most acceptable compromise solution to
    adjust this issue by moving skb_add_rx_frag() into conditional scope.
    
    Found by Linux Verification Center (linuxtesting.org) with SVACE.
    
    Fixes: 1f233f327913 ("liquidio: switchdev support for LiquidIO NIC")
    Signed-off-by: Aleksandr Mishin <amishin@xxxxxxxxxx>
    Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
index a1bda1683ebfc..d90500573f5b7 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
@@ -289,13 +289,12 @@ lio_vf_rep_copy_packet(struct octeon_device *oct,
 				pg_info->page_offset;
 			memcpy(skb->data, va, MIN_SKB_SIZE);
 			skb_put(skb, MIN_SKB_SIZE);
+			skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+					pg_info->page,
+					pg_info->page_offset + MIN_SKB_SIZE,
+					len - MIN_SKB_SIZE,
+					LIO_RXBUFFER_SZ);
 		}
-
-		skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
-				pg_info->page,
-				pg_info->page_offset + MIN_SKB_SIZE,
-				len - MIN_SKB_SIZE,
-				LIO_RXBUFFER_SZ);
 	} else {
 		struct octeon_skb_page_info *pg_info =
 			((struct octeon_skb_page_info *)(skb->cb));