Re: [PATCH 4/5] Src/module: fix use-after-free in setmathfuncs()

[Mikael Magnusson <mikachu@gmail.com>]

On 11/7/18, Kamil Dudka <kdudka@redhat.com> wrote:
> Detected by Coverity Analysis:
>
> Error: USE_AFTER_FREE (CWE-825):
> zsh-5.5.1/Src/module.c:1390: freed_arg: "deletemathfunc" frees "f".
> zsh-5.5.1/Src/module.c:1352:6: freed_arg: "zfree" frees parameter "f".
> zsh-5.5.1/Src/mem.c:1888:5: freed_arg: "free" frees parameter "p".
> zsh-5.5.1/Src/module.c:1394: deref_after_free: Dereferencing freed pointer
> "f".
> 1392|   		ret = 1;
> 1393|   	    } else {
> 1394|-> 		f->flags &= ~MFF_ADDED;
> 1395|   	    }
> 1396|   	}
> ---
>  Src/module.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/Src/module.c b/Src/module.c
> index 4ae78310f..33d75ebbd 100644
> --- a/Src/module.c
> +++ b/Src/module.c
> @@ -1390,8 +1390,6 @@ setmathfuncs(char const *nam, MathFunc f, int size,
> int *e)
>  	    if (deletemathfunc(f)) {
>  		zwarnnam(nam, "math function `%s' already deleted", f->name);
>  		ret = 1;
> -	    } else {
> -		f->flags &= ~MFF_ADDED;
>  	    }
>  	}
>  	f++;
> --
> 2.17.2

In the other branch, if f was already deleted, how can we use f->name there?

-- 
Mikael Magnusson