tile: sanitize copy_thread()

Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 11 insertions, 13 deletions

diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index 6e7fb4e41f1c..1c20029d2f5a 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -158,7 +158,7 @@ static void save_arch_state(struct thread_struct *t);
 
 int copy_thread(unsigned long clone_flags, unsigned long sp,
                 unsigned long arg,
-                struct task_struct *p, struct pt_regs *regs)
+                struct task_struct *p, struct pt_regs *unused)
 {
         struct pt_regs *childregs = task_pt_regs(p);
         unsigned long ksp;
@@ -184,7 +184,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
         /* Record the pid of the task that created this one. */
         p->thread.creator_pid = current->pid;
 
-        if (unlikely(!regs)) {
+        if (unlikely(p->flags & PF_KTHREAD)) {
                 /* kernel thread */
                 memset(childregs, 0, sizeof(struct pt_regs));
                 memset(&callee_regs[2], 0,
@@ -208,25 +208,26 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
          */
         task_thread_info(p)->step_state = NULL;
 
-        /* Save user stack top pointer so we can ID the stack vm area later. */
-        p->thread.usp0 = sp;
-
         /*
          * Copy the registers onto the kernel stack so the
          * return-from-interrupt code will reload it into registers.
          */
-        *childregs = *regs;
+        *childregs = *current_pt_regs();
         childregs->regs[0] = 0;         /* return value is zero */
-        childregs->sp = sp;  /* override with new user stack pointer */
-        memcpy(callee_regs, &regs->regs[CALLEE_SAVED_FIRST_REG],
+        if (sp)
+                childregs->sp = sp;  /* override with new user stack pointer */
+        memcpy(callee_regs, &childregs->regs[CALLEE_SAVED_FIRST_REG],
                CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
 
+        /* Save user stack top pointer so we can ID the stack vm area later. */
+        p->thread.usp0 = childregs->sp;
+
         /*
          * If CLONE_SETTLS is set, set "tp" in the new task to "r4",
          * which is passed in as arg #5 to sys_clone().
          */
         if (clone_flags & CLONE_SETTLS)
-                childregs->tp = regs->regs[4];
+                childregs->tp = childregs->regs[4];
 
 
 #if CHIP_HAS_TILE_DMA()
@@ -587,10 +588,7 @@ int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
 SYSCALL_DEFINE4(clone, unsigned long, clone_flags, unsigned long, newsp,
                 void __user *, parent_tidptr, void __user *, child_tidptr)
 {
-        struct pt_regs *regs = current_pt_regs();
-        if (!newsp)
-                newsp = regs->sp;
-        return do_fork(clone_flags, newsp, regs, 0,
+        return do_fork(clone_flags, newsp, current_pt_regs(), 0,
                        parent_tidptr, child_tidptr);
 }