Possible bug on signal.h

[Jordi Brinquez <jordi.brinquez@gmail.com>]

Hi,

I think I found a possible bug on file signal.h.

The problem comes when you define a struct sigaction on a user program
and then you use the function sigaction to remap a signal handler (in
my case a page_fault) for my own function, this system call is
compiled as __NR_sigaction system call (by default this routine is
managed by sys_sigaction routine) and if the architecture defines
__ARCH_WANT_SYS_RT_SIGACTION kernel uses the routine sys_rt_sigaction
on the file kernel/signal.c that instead of copying the fields from
one structure to the other it just uses copy_from_user and
copy_to_user with the consequent mess with the fields.

One possible solution will be to change the field order in all struct
sigaction under arch/ folder and reorder the fields exactly the same
as in the kernel definition (on kernel mode are defined in this order
sa_handler, sa_flags, sa_restorer, sa_mask and on user mode
_sa_handler | _sa_sigaction, sa_mask, sa_flags, sa_restorer).

Another solution will be change the copy_to_user and copy_from_user
for calls like in arch/i386/kernel/signal.c (__get_user(...) and
__put_user(...)).

Or what I think it will be better change both.

I've been searching and I think that the affected architectures are
those ones, but I may forgot some:

- arm
- arm26
- cris
- i386
- m32r
- m68k
- m68knommu
- s390
- sh
- sh64
- sparc64
- um
- v850

Hope I explained the problem quite clear if not please ask for more
info and I'll give you all that you need.

Greets,

Jordi