netdev - [PATCH 1/8] netfilter: ebtables: fix a memory leak bug in compat

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Message-Id: <20190731115157.27020-2-pablo@netfilter.org>
Date:   Wed, 31 Jul 2019 13:51:50 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 1/8] netfilter: ebtables: fix a memory leak bug in compat

From: Wenwen Wang <wenwen@...uga.edu>

In compat_do_replace(), a temporary buffer is allocated through vmalloc()
to hold entries copied from the user space. The buffer address is firstly
saved to 'newinfo->entries', and later on assigned to 'entries_tmp'. Then
the entries in this temporary buffer is copied to the internal kernel
structure through compat_copy_entries(). If this copy process fails,
compat_do_replace() should be terminated. However, the allocated temporary
buffer is not freed on this path, leading to a memory leak.

To fix the bug, free the buffer before returning from compat_do_replace().

Signed-off-by: Wenwen Wang <wenwen@...uga.edu>
Reviewed-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/bridge/netfilter/ebtables.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 963dfdc14827..fd84b48e48b5 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2261,8 +2261,10 @@ static int compat_do_replace(struct net *net, void __user *user,
 	state.buf_kern_len = size64;

 	ret = compat_copy_entries(entries_tmp, tmp.entries_size, &state);
-	if (WARN_ON(ret < 0))
+	if (WARN_ON(ret < 0)) {
+		vfree(entries_tmp);
 		goto out_unlock;
+	}

 	vfree(entries_tmp);
 	tmp.entries_size = size64;
-- 
2.11.0