selftests: xfrm: fix test return value override issue in xfrm_policy.sh

stable inclusion
from stable-5.10.13
commit 8ea899803bb5c9d3cfb60d75d0c40f68f8227abe
bugzilla: 47995

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

[ Upstream commit f6e9ceb7 ]

When running this xfrm_policy.sh test script, even with some cases
marked as FAIL, the overall test result will still be PASS:

$ sudo ./xfrm_policy.sh
PASS: policy before exception matches
FAIL: expected ping to .254 to fail (exceptions)
PASS: direct policy matches (exceptions)
PASS: policy matches (exceptions)
FAIL: expected ping to .254 to fail (exceptions and block policies)
PASS: direct policy matches (exceptions and block policies)
PASS: policy matches (exceptions and block policies)
FAIL: expected ping to .254 to fail (exceptions and block policies after hresh changes)
PASS: direct policy matches (exceptions and block policies after hresh changes)
PASS: policy matches (exceptions and block policies after hresh changes)
FAIL: expected ping to .254 to fail (exceptions and block policies after hthresh change in ns3)
PASS: direct policy matches (exceptions and block policies after hthresh change in ns3)
PASS: policy matches (exceptions and block policies after hthresh change in ns3)
FAIL: expected ping to .254 to fail (exceptions and block policies after htresh change to normal)
PASS: direct policy matches (exceptions and block policies after htresh change to normal)
PASS: policy matches (exceptions and block policies after htresh change to normal)
PASS: policies with repeated htresh change
$ echo $?
0

This is because the $lret in check_xfrm() is not a local variable.
Therefore when a test failed in check_exceptions(), the non-zero $lret
will later get reset to 0 when the next test calls check_xfrm().

With this fix, the final return value will be 1. Make it easier for
testers to spot this failure.

Fixes: 39aa6928 ("xfrm: policy: fix netlink/pf_key policy lookups")
Signed-off-by: NPo-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

tools/testing/selftests/net/xfrm_policy.sh

@@ -202,7 +202,7 @@ check_xfrm() {
 	# 1: iptables -m policy rule count != 0
 	rval=$1
 	ip=$2
-	lret=0
+	local lret=0
 
 	ip netns exec ns1 ping -q -c 1 10.0.2.$ip > /dev/null