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, 2 insertions, 0 deletions

diff --git a/sys/kern/kern_thr.c b/sys/kern/kern_thr.c
index de45d0a..6bf0ded 100644
--- a/sys/kern/kern_thr.c
+++ b/sys/kern/kern_thr.c
@@ -175,6 +175,8 @@ create_thread(struct thread *td, mcontext_t *ctx,
 
 	/* Initialize our td */
 	newtd = thread_alloc();
+	if (newtd == NULL)
+		return (ENOMEM);
 
 	/*
 	 * Try the copyout as soon as we allocate the td so we don't