tile: sanitize copy_thread()
Al Viro [Wed, 24 Oct 2012 03:32:21 +0000 (23:32 -0400)]
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/tile/kernel/process.c

index 6e7fb4e..1c20029 100644 (file)
@@ -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);
 }