Re: Is it legal to return positive value when do_execve() succeeds?

[KOSAKI Motohiro]

> > KOSAKI Motohiro wrote:
> > > > fs/binfmt_elf.c:
> > > >  77 #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
> > > Can do_brk() return BAD_ADDR() _and_ !IS_ERR_VALUE() value? when?
> > 
> > For example, arch/mips/include/asm/processor.h has below definitions
> > which is smaller than INT_MAX
> > 
> >  47 #ifdef CONFIG_32BIT
> > (...snipped...)
> >  52 #define TASK_SIZE       0x7fff8000UL
> > (...snipped...)
> >  63 #endif
> >  64 
> >  65 #ifdef CONFIG_64BIT
> > (...snipped...)
> >  74 #define TASK_SIZE       0x10000000000UL
> > (...snipped...)
> >  91 #endif
> > 
> > Also, several architectures define TASK_SIZE as
> > 
> >   #define TASK_SIZE               PAGE_OFFSET
> > 
> > and PAGE_OFFSET could be 0 if CONFIG_KERNEL_RAM_BASE_ADDRESS is not defined.
> > 
> > include/asm-generic/page.h
> >  68 #ifdef CONFIG_KERNEL_RAM_BASE_ADDRESS
> >  69 #define PAGE_OFFSET             (CONFIG_KERNEL_RAM_BASE_ADDRESS)
> >  70 #else
> >  71 #define PAGE_OFFSET             (0)
> >  72 #endif
> > 
> > If TASK_SIZE == 0, BAD_ADDR(x) is always true and !IS_ERR_VALUE(x) can be true.
> > Although I don't know which combination makes such environment,
> > I think "BAD_ADDR() _and_ !IS_ERR_VALUE()" can happen.
> 
> I think you should read do_brk() itself. the spec is
> 
> success case:
> 	return addr argument
> 
> error case: 
> 	return error code
> 
> When does it return invalid address?

Does this makes a bit cleanups?