[Devel] [PATCH RHEL7 COMMIT] rh/qede: confirm skb is allocated before using

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-1160.80.1.vz7.191.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.80.1.vz7.191.4
------>
commit 9317d611891479b480b78ea85810243732c09bc9
Author: Jamie Bainbridge <jamie.bainbridge at gmail.com>
Date:   Wed Apr 6 21:19:19 2022 +1000

    rh/qede: confirm skb is allocated before using
    
    qede_build_skb() assumes build_skb() always works and goes straight
    to skb_reserve(). However, build_skb() can fail under memory pressure.
    This results in a kernel panic because the skb to reserve is NULL.
    
    Add a check in case build_skb() failed to allocate and return NULL.
    
    The NULL return is handled correctly in callers to qede_build_skb().
    
    mFixes: 8a8633978b842 ("qede: Add build_skb() support.")
    Signed-off-by: Jamie Bainbridge <jamie.bainbridge at gmail.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>
    
    The patch is backported from RHEL7.9 kernel 3.10.0-1160.81.1.el7:
    https://access.redhat.com/labs/rhcb/RHEL-7.9/kernel-3.10.0-1160.81.1.el7/patches/blob/1508-netdrv-qede-confirm-skb-is-allocated-before-using.patch
    
      From: Jamie Bainbridge <jbainbri at redhat.com>
      Date: Fri, 30 Sep 2022 15:34:57 +1000
      Subject: [PATCH 1508/1510] [netdrv] qede: confirm skb is allocated
               before using
      Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2131145
    
    https://jira.sw.ru/browse/PSBM-144136
    (cherry picked from ms commit 4e910dbe36508654a896d5735b318c0b88172570)
    Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 drivers/net/ethernet/qlogic/qede/qede_fp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/qlogic/qede/qede_fp.c b/drivers/net/ethernet/qlogic/qede/qede_fp.c
index b3ea11a1d07f..43844f8f4be3 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_fp.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_fp.c
@@ -731,6 +731,9 @@ qede_build_skb(struct qede_rx_queue *rxq,
 	buf = page_address(bd->data) + bd->page_offset;
 	skb = build_skb(buf, rxq->rx_buf_seg_size);
 
+	if (unlikely(!skb))
+		return NULL;
+
 	skb_reserve(skb, pad);
 	skb_put(skb, len);