netlink: fix stack overflow due to erroneous rounding

Byteorder switch in this function may undersize the conversion
buffer by one byte, this needs to use div_round_up().

Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/shell/testcases/bogons/nft-f/byteorder_switch_stack_overflow b/tests/shell/testcases/bogons/nft-f/byteorder_switch_stack_overflow
new file mode 100644
index 00000000..01640528
--- /dev/null
+++ b/tests/shell/testcases/bogons/nft-f/byteorder_switch_stack_overflow
@@ -0,0 +1,6 @@
+table inet x {
+	chain nat_dns_acme {
+		udp length . @th,260,118 vmap { 47-63 . 0xe373135363130333131303735353203 : goto nat_dns_dnstc, }
+		drop
+	}
+}