[PATCH AUTOSEL 4.14 05/44] netfilter: ebtables: fix a memory leak bug in compat

Sasha Levin
2019-08-14T02:22:39Z

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

[ Upstream commit 15a78ba1844a8e052c1226f930133de4cef4e7ad ]

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@cs.uga.edu>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.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 b967bd51bf1f9..48e364b11e067 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2267,8 +2267,10 @@ 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;
--
2.20.1