Re: [PATCH nft] parser_bison: fix memory leak when parsing flowtable hook declaration

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Wed, Jul 23, 2025 at 05:00:11PM +0200, Florian Westphal wrote:
> When the hook location is invalid we error out but we do leak both
> the priority expression and the flowtable name.  Example:
> 
> valgrind --leak-check=full nft -f flowtable-parser-err-memleak
> [..] Error: unknown chain hook
> hook enoent priority filter + 10
>      ^^^^^^
> [..]
> 2 bytes in 1 blocks are definitely lost in loss record 1 of 3
>    at: malloc (vg_replace_malloc.c:446)
>    by: strdup (in libc.so.6)
>    by: xstrdup (in libnftables.so.1.1.0)
>    by: nft_lex (in libnftables.so.1.1.0)
>    by: nft_parse (in libnftables.so.1.1.0)
>    by: __nft_run_cmd_from_filename (in libnftables.so.1.1.0)
>    by: nft_run_cmd_from_filename (in libnftables.so.1.1.0)
> 
> First two reports are due to the priority expression: this needs to call
> expr_free().  Third report is due to the flowtable name, the destructor
> was missing so add one.
> 
> After fix:
> All heap blocks were freed -- no leaks are possible
> 
> Signed-off-by: Florian Westphal <fw@strlen.de>

Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>

Thanks