linux-kernel - [PATCH] ip_sockglue: Fix a missing-check bug in net/ipv4/ip

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Message-ID: <20190521084759.GJ5263@zhanggen-UX430UQ>
Date:   Tue, 21 May 2019 16:47:59 +0800
From:   Gen Zhang <blackgod016574@...il.com>
To:     kuznet@....inr.ac.ru
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] ip_sockglue: Fix a missing-check bug in
 net/ipv4/ip_sockglue.c

In function ip_ra_control(), the pointer new_ra is allocated a memory 
space via kmalloc(). And it is used in the following codes. However, 
when  there is a memory allocation error, kmalloc() fails. Thus null 
pointer dereference may happen. And it will cause the kernel to crash. 
Therefore, we should check the return value and handle the error.

Signed-off-by: Gen Zhang <blackgod016574@...il.com>

---
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 82f341e..aa3fd61 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -343,6 +343,8 @@ int ip_ra_control(struct sock *sk, unsigned char on,
 		return -EINVAL;

 	new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL;
+	if (on && !new_ra)
+		return -ENOMEM;

 	mutex_lock(&net->ipv4.ra_mutex);
 	for (rap = &net->ipv4.ra_chain;