Re: [PATCH] Fix invalid free of memory allocated during rtld init

[Carlos O'Donell <carlos at systemhalted dot org>]

On 01/15/2013 11:04 AM, Andreas Schwab wrote:
> Any memory allocated during rtld init cannot be freed.
> 
> Andreas.
> 
> 	[BZ #14293]
> 	* elf/dl-load.c (_dl_init_paths): Mark decomposed RUNPATH as
> 	non-freeable.
> 
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index 6e65980..a3aab8a 100644
> --- a/elf/dl-load.c
> +++ b/elf/dl-load.c
> @@ -797,6 +797,7 @@ _dl_init_paths (const char *llp)
>  			   (const void *) (D_PTR (l, l_info[DT_STRTAB])
>  					   + l->l_info[DT_RUNPATH]->d_un.d_val),
>  			   l, "RUNPATH");
> +	  l->l_runpath_dirs.malloced = 0;
>  
>  	  /* The RPATH is ignored.  */
>  	  l->l_rpath_dirs.dirs = (void *) -1;
> 

As you work on the problem you familiarize yourself
with the code in question and it seems obvious to you that
this one line change is the solution to the problem.

For example those familiar with the code know that malloc
can't be called during early relocation, instead we use
a dummy allocator for which we can't call free later.

Unfortunately, even to the reviewer, me, it doesn't
make it any easier to review because you have not provided 
sufficient information to help me review. In particular
I need three things:
(a) assumptions, 
(b) analysis and 
(c) conclusions.

Stating (c) directly without (a) or (b) means that I as 
the reviewer need to create (a) and (b) *without* your 
help and compare them to (c). This increases the burden
on the reviewer significantly.

Could you please help by posting (a) and (b)?

Cheers,
Carlos.