[PATCH nft] parser_bison: string memleak in YYERROR path

[PATCH nft] parser_bison: string memleak in YYERROR path

[Pablo Neira Ayuso]

Release dynamically allocated string by lex from the YYERROR path, e.g.

 # cat test.nft
 table x {
        map test {
                type ipv4_addr . foo . inet_service : ipv4_addr . inet_service
        }
 }

 # nft -f test.nft
test.nft:3:20-22: Error: unknown datatype foo
                type ipv4_addr . foo . inet_service : ipv4_addr . inet_service
                                 ^^^
test.nft:6-9: Error: set definition does not specify key
        map test {
            ^^^^
 ==29692==ERROR: LeakSanitizer: detected memory leaks

 Direct leak of 5 byte(s) in 1 object(s) allocated from:
    #0 0x7f6c869e8810 in strdup (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x3a810)
    #1 0x7f6c8637f63a in xstrdup /home/test/nftables/src/utils.c:85
    #2 0x7f6c8648a4d3 in nft_lex /home/test/nftables/src/scanner.l:740

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
Supersedes: https://patchwork.ozlabs.org/project/netfilter-devel/patch/20210623111249.30742-1-pablo@netfilter.org/

 src/parser_bison.y | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/parser_bison.y b/src/parser_bison.y
index c31cc4e7ea8f..e405c80af1ff 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -972,6 +972,7 @@ common_block		:	INCLUDE		QUOTED_STRING	stmt_separator
 				if (symbol_unbind(scope, $2) < 0) {
 					erec_queue(error(&@2, "undefined symbol '%s'", $2),
 						   state->msgs);
+					xfree($2);
 					YYERROR;
 				}
 				xfree($2);
@@ -2162,6 +2163,7 @@ data_type_atom_expr	:	type_identifier
 				if (dtype == NULL) {
 					erec_queue(error(&@1, "unknown datatype %s", $1),
 						   state->msgs);
+					xfree($1);
 					YYERROR;
 				}
 				$$ = constant_expr_alloc(&@1, dtype, dtype->byteorder,
@@ -2717,6 +2719,7 @@ comment_spec		:	COMMENT		string
 					erec_queue(error(&@2, "comment too long, %d characters maximum allowed",
 							 NFTNL_UDATA_COMMENT_MAXLEN),
 						   state->msgs);
+					xfree($2);
 					YYERROR;
 				}
 				$$ = $2;
-- 
2.20.1