[PATCH nft] parser_bison: close chain scope before chain release

[Florian Westphal <fw@strlen.de>]

cmd_alloc() will free the chain, so we must close the scope opened
in chain_block_alloc beforehand.

The included test file will cause a use-after-free because nft attempts
to search for an identifier in a scope that has been freed:

AddressSanitizer: heap-use-after-free on address 0x618000000368 at pc 0x7f1cbc0e6959 bp 0x7ffd3ccb7850 sp 0x7ffd3ccb7840
    #0 0x7f1cbc0e6958 in symbol_lookup src/rule.c:629
    #1 0x7f1cbc0e66a1 in symbol_get src/rule.c:588
    #2 0x7f1cbc120d67 in nft_parse src/parser_bison.y:4325

Fixes: a66b5ad9540d ("src: allow for updating devices on existing netdev chain")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 src/parser_bison.y                                           | 1 +
 .../testcases/bogons/nft-f/use_after_free_on_chain_removal   | 5 +++++
 2 files changed, 6 insertions(+)
 create mode 100644 tests/shell/testcases/bogons/nft-f/use_after_free_on_chain_removal

diff --git a/src/parser_bison.y b/src/parser_bison.y
index e1addc26d20d..44d440f762e7 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -1419,6 +1419,7 @@ delete_cmd		:	TABLE		table_or_id_spec
 			{
 				$5->location = @5;
 				handle_merge(&$3->handle, &$2);
+				close_scope(state);
 				$$ = cmd_alloc(CMD_DELETE, CMD_OBJ_CHAIN, &$2, &@$, $5);
 			}
 			|	RULE		ruleid_spec
diff --git a/tests/shell/testcases/bogons/nft-f/use_after_free_on_chain_removal b/tests/shell/testcases/bogons/nft-f/use_after_free_on_chain_removal
new file mode 100644
index 000000000000..bb9632b053be
--- /dev/null
+++ b/tests/shell/testcases/bogons/nft-f/use_after_free_on_chain_removal
@@ -0,0 +1,5 @@
+delete	chain d iUi {
+}}
+delete	chain d hUi {
+delete	chain o
+c b icmpv6  id$i
-- 
2.41.0