linux-kernel - Re: [PATCH v3 01/13] tools lib bpf: Check return value of strdup when reading map names

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Message-ID: <20151130084018.GA14252@danjae.kornet>
Date:	Mon, 30 Nov 2015 17:40:18 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	acme@...nel.org, masami.hiramatsu.pt@...achi.com, ast@...nel.org,
	lizefan@...wei.com, pi3orama@....com, linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH v3 01/13] tools lib bpf: Check return value of strdup
 when reading map names

On Mon, Nov 30, 2015 at 07:32:01AM +0000, Wang Nan wrote:
> Commit 561bbccac72d08babafaa33fd7fa9100ec4c9fb6 ("tools lib bpf:
> Extract and collect map names from BPF object file") forgets checking
> return value of strdup(). This patch fixes it. It also checks names
> pointer before strcmp() for safty.
> 
> Reported-by: Namhyung Kim <namhyung@...nel.org>
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>

Acked-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung


> ---
>  tools/lib/bpf/libbpf.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index a298614..16485ab 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -527,14 +527,14 @@ bpf_object__init_maps(struct bpf_object *obj, void *data,
>  	return 0;
>  }
>  
> -static void
> +static int
>  bpf_object__init_maps_name(struct bpf_object *obj, int maps_shndx)
>  {
>  	int i;
>  	Elf_Data *symbols = obj->efile.symbols;
>  
>  	if (!symbols || maps_shndx < 0)
> -		return;
> +		return -EINVAL;
>  
>  	for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
>  		GElf_Sym sym;
> @@ -556,9 +556,14 @@ bpf_object__init_maps_name(struct bpf_object *obj, int maps_shndx)
>  			continue;
>  		}
>  		obj->maps[map_idx].name = strdup(map_name);
> +		if (!obj->maps[map_idx].name) {
> +			pr_warning("failed to alloc map name\n");
> +			return -ENOMEM;
> +		}
>  		pr_debug("map %zu is \"%s\"\n", map_idx,
>  			 obj->maps[map_idx].name);
>  	}
> +	return 0;
>  }
>  
>  static int bpf_object__elf_collect(struct bpf_object *obj)
> @@ -663,7 +668,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
>  	}
>  
>  	if (maps_shndx >= 0)
> -		bpf_object__init_maps_name(obj, maps_shndx);
> +		err = bpf_object__init_maps_name(obj, maps_shndx);
>  out:
>  	return err;
>  }
> @@ -1372,7 +1377,7 @@ bpf_object__get_map_by_name(struct bpf_object *obj, const char *name)
>  	struct bpf_map *pos;
>  
>  	bpf_map__for_each(pos, obj) {
> -		if (strcmp(pos->name, name) == 0)
> +		if (pos->name && !strcmp(pos->name, name))
>  			return pos;
>  	}
>  	return NULL;
> -- 
> 1.8.3.4
> 
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