netfilter: ebtables: fix memory leak when blob is malformed

stable inclusion
from stable-v4.19.260
commit 1e98318af2f163eadaff815abcef38d27ca92c1e
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5UQH4


CVE: NA

--------------------------------

[ Upstream commit 62ce44c4 ]

The bug fix was incomplete, it "replaced" crash with a memory leak.
The old code had an assignment to "ret" embedded into the conditional,
restore this.

Fixes: 7997eff8 ("netfilter: ebtables: reject blobs that don't provide all entry points")
Reported-and-tested-by:  <syzbot+a24c5252f3e3ab733464@syzkaller.appspotmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Xu Jia <xujia39@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>