Re: dhcp server null pointer in option_cache_dereference

[Sad Clouds]

On Wed, 12 Aug 2020 13:44:27 +0100 (BST)
Stephen Borrill <net...@precedence.co.uk> wrote:

> On some machines newly upgraded to 9.0_STABLE, dhcp runs fine for,
> say, 24 hours then starts logging the following. After this point, it
> no longer handles any DHCP requests:
> 
> Null pointer in option_cache_dereference: 
> /usr/src/external/mpl/dhcp/bin/server/../../dist/server/dhcp.c(4067)
> 
> That 4067 is meant to be a line number according to
> dist/common/options.c, but there's no call to
> option_cache_dereference() at line 4067. Also, most calls to
> option_cache_dereference() don't specify the line as the third
> option, but I may be missing something.
> 
> Any ideas?
> 
> -- 
> Stephen
> 

I would say build with POINTER_DEBUG and then get a core dump. This
should tell you where this happens.

int option_cache_dereference (ptr, file, line)
        struct option_cache **ptr;
        const char *file;
        int line;
{
        if (!ptr || !*ptr) {
                log_error ("Null pointer in option_cache_dereference: %s(%d)",
                           file, line);
#if defined (POINTER_DEBUG)
                abort ();
#else
                return 0;
#endif
        }