[PATCH nft 3/6] parser: don't assert on scope underflows

[Florian Westphal <fw@strlen.de>]

close_scope() gets called from the object destructors;
imbalance can cause us to hit assert().

Before:
nft: parser_bison.y:88: close_scope: Assertion `state->scope > 0' failed.
After:
assertion3:4:7-7: Error: too many levels of nesting jump {
assertion3:5:8-8: Error: too many levels of nesting jump
assertion3:5:9-9: Error: syntax error, unexpected newline, expecting '{'
assertion3:7:1-1: Error: syntax error, unexpected end of file

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 src/parser_bison.y                                        | 3 +--
 tests/shell/testcases/bogons/nft-f/scope_underflow_assert | 6 ++++++
 2 files changed, 7 insertions(+), 2 deletions(-)
 create mode 100644 tests/shell/testcases/bogons/nft-f/scope_underflow_assert

diff --git a/src/parser_bison.y b/src/parser_bison.y
index 763c1b2dcd61..f5f6bf04d064 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -80,12 +80,11 @@ static int open_scope(struct parser_state *state, struct scope *scope)
 
 static void close_scope(struct parser_state *state)
 {
-	if (state->scope_err) {
+	if (state->scope_err || state->scope == 0) {
 		state->scope_err = false;
 		return;
 	}
 
-	assert(state->scope > 0);
 	state->scope--;
 }
 
diff --git a/tests/shell/testcases/bogons/nft-f/scope_underflow_assert b/tests/shell/testcases/bogons/nft-f/scope_underflow_assert
new file mode 100644
index 000000000000..aee1dcbf9d8a
--- /dev/null
+++ b/tests/shell/testcases/bogons/nft-f/scope_underflow_assert
@@ -0,0 +1,6 @@
+table t {
+	chain c {
+		jump{
+			jump {
+				jump
+
-- 
2.39.3