Re: [XenPPC] [PATCH] Check for NULL source pointer

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

On Tue, 2007-03-27 at 19:18 -0400, Amos Waterland wrote:
> While debugging the zImage problem on a JS21, I noticed that DOM0
> bootargs was filled with bogus characters.  I believe something like
> this is necessary.
> 
> Signed-off-by: Amos Waterland <apw@xxxxxxxxxx>
> 
> ---
> 
>  ofd_fixup.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff -r cc72b77132f9 xen/arch/powerpc/ofd_fixup.c
> --- a/xen/arch/powerpc/ofd_fixup.c    Wed Mar 21 18:29:49 2007 -0500
> +++ b/xen/arch/powerpc/ofd_fixup.c    Tue Mar 27 19:13:03 2007 -0400
> @@ -276,7 +276,10 @@ static ofdn_t ofd_chosen_props(void *m, 
>                       &path[1], sizeof (path) - 1);
>      }
> 
> -    strlcpy(bootargs, cmdline, sizeof(bootargs));
> +    memset(bootargs, 0, sizeof(bootargs));
> +    if (cmdline) {
> +        strlcpy(bootargs, cmdline, sizeof(bootargs));
> +    }
>      bsz = strlen(bootargs) + 1;
>      rm = sizeof (bootargs) - bsz;

Scary, it looks like we're doing strlen(NULL) in strlcpy(), which must
be returning a non-0 length (since the memory at 0 actually contains
instructions).

Nice catch, thanks.

-- 
Hollis Blanchard
IBM Linux Technology Center


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