Re: [PATCH 2/2] tools/bpftool: Fix segfault case regarding 'pin' arguments

[Jakub Kicinski]

On Wed, 18 Jul 2018 22:35:26 +0900, Taeung Song wrote:
> Arguments of 'pin' subcommand should be checked
> at the very beginning of do_pin_any().
> Otherwise segfault errors can occur when using
> 'map pin' or 'prog pin' commands, so fix it.
> 
>   # bpftool prog pin id
>   Segmentation fault
> 
> Fixes: 71bb428fe2c1 ("tools: bpf: add bpftool")
> Cc: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
> Reported-by: Taehee Yoo <ap420073@xxxxxxxxx>
> Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
> ---
>  tools/bpf/bpftool/common.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
> index 32f9e397a6c0..b1e1ba9e1c90 100644
> --- a/tools/bpf/bpftool/common.c
> +++ b/tools/bpf/bpftool/common.c
> @@ -217,6 +217,14 @@ int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(__u32))
>  	int err;
>  	int fd;
>  
> +	if (argc < 3) {
> +		p_err("too few arguments, id PROG_ID and FILE path is required");

Thanks for the fix!  You can't say PROG_ID here, because this function
is also called by bpftool map pin id X.  How about s/PROG_ID/ID/ ?

> +		return -1;
> +	} else if (argc > 3) {
> +		p_err("too many arguments");
> +		return -1;
> +	}
> +
>  	if (!is_prefix(*argv, "id")) {
>  		p_err("expected 'id' got %s", *argv);
>  		return -1;
> @@ -230,9 +238,6 @@ int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(__u32))
>  	}
>  	NEXT_ARG();
>  
> -	if (argc != 1)
> -		usage();
> -
>  	fd = get_fd_by_id(id);
>  	if (fd < 0) {
>  		p_err("can't get prog by id (%u): %s", id, strerror(errno));