linux-kernel - [BUG] ipv6: possible null-pointer dereference in ip6

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Date:   Tue, 10 Aug 2021 21:46:13 +0800
From:   Tuo Li <islituo@...il.com>
To:     john.fastabend@...il.com, kpsingh@...nel.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org, baijiaju1990@...il.com
Subject: [BUG] ipv6: possible null-pointer dereference in ip6_xmit()

Hello,

Our static analysis tool finds a possible null-pointer dereference in 
ip6_output.c in Linux 5.14.0-rc3:

The variable n is checked in:
314:    if (np)

This indicates that it can be NULL. If so, a null-pointer dereference 
will occur
in the called function ip6_autoflowlabel() at Line 320:
252:    if (!np->autoflowlabel_set)

I am not quite sure whether this possible null-pointer dereference is 
real and how to fix it if it is real.
Any feedback would be appreciated, thanks!

Reported-by: TOTE Robot <oslab@...nghua.edu.cn>

Best wishes,
Tuo Li