Fix for the panic("vm_thread_new: kstack allocation failed") and

silent NULL pointer dereference in the i386 and sparc64 pmap_pinit()
when the kmem_alloc_nofault() failed to allocate address space. Both
functions now return error instead of panicing or dereferencing NULL.

As consequence, vmspace_exec() and vmspace_unshare() returns the errno
int. struct vmspace arg was added to vm_forkproc() to avoid dealing
with failed allocation when most of the fork1() job is already done.

The kernel stack for the thread is now set up in the thread_alloc(),
that itself may return NULL. Also, allocation of the first process
thread is performed in the fork1() to properly deal with stack
allocation failure. proc_linkup() is separated into proc_linkup()
called from fork1(), and proc_linkup0(), that is used to set up the
kernel process (was known as swapper).

In collaboration with:	Peter Holm
Reviewed by:	jhb

1 files changed, 3 insertions, 1 deletions

diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index d2798db..80ef703 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -914,7 +914,9 @@ exec_new_vmspace(imgp, sv)
 		pmap_remove_pages(vmspace_pmap(vmspace));
 		vm_map_remove(map, vm_map_min(map), vm_map_max(map));
 	} else {
-		vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser);
+		error = vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser);
+		if (error)
+			return (error);
 		vmspace = p->p_vmspace;
 		map = &vmspace->vm_map;
 	}