tests: cover baecd1cf2685 ("segtree: Fix segfault when restoring a huge interval...

Test inspired by [1] with both the set and stack size reduced by the
same power of 2, to preserve the (pre-baecd1cf2685) segfault on one
hand, and make the test successfully complete (post-baecd1cf2685) in a
few seconds even on weaker hardware on the other.

(The reason I stopped at 128kB stack size is that with 64kB I was
getting segfaults even with baecd1cf2685 applied.)

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1908127

Signed-off-by: Štěpán Němec <snemec@redhat.com>
Helped-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Phil Sutter <phil@nwl.cc>

diff --git a/tests/shell/testcases/sets/0068interval_stack_overflow_0 b/tests/shell/testcases/sets/0068interval_stack_overflow_0
new file mode 100755 (executable)
index 0000000..134282d
--- /dev/null
+++ b/tests/shell/testcases/sets/0068interval_stack_overflow_0
@@ -0,0 +1,29 @@
+#!/bin/bash
+
+set -e
+
+ruleset_file=$(mktemp)
+
+trap 'rm -f "$ruleset_file"' EXIT
+
+{
+       echo 'define big_set = {'
+       for ((i = 1; i < 255; i++)); do
+               for ((j = 1; j < 80; j++)); do
+                       echo "10.0.$i.$j,"
+               done
+       done
+       echo '10.1.0.0/24 }'
+} >"$ruleset_file"
+
+cat >>"$ruleset_file" <<\EOF
+table inet test68_table {
+       set test68_set {
+               type ipv4_addr
+               flags interval
+               elements = { $big_set }
+       }
+}
+EOF
+
+( ulimit -s 128 && "$NFT" -f "$ruleset_file" )