[PATCH 4.14 04/62] netfilter: ebtables: fix a memory leak bug in compat

From: Greg Kroah-Hartman
Date: Tue Aug 27 2019 - 03:51:52 EST

[ 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@xxxxxxxxxx>
Reviewed-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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 f9c6e8ca1fcb0..100b4f88179a2 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2273,8 +2273,10 @@ 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;
+ }

tmp.entries_size = size64;