[PATCH] powerpc/ptrace: Use copy_{from, to}_user() rather than open-coding

[Michael Ellerman]

From: Al Viro <v...@zeniv.linux.org.uk>

In PPC_PTRACE_GETHWDBGINFO and PPC_PTRACE_SETHWDEBUG we do an
access_ok() check and then __copy_{from,to}_user().

Instead we should just use copy_{from,to}_user() which does all that
for us and is less error prone.

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
 arch/powerpc/kernel/ptrace.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 0f63dd5972e9..9667666eb18e 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -3082,27 +3082,19 @@ long arch_ptrace(struct task_struct *child, long 
request,
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 #endif /* CONFIG_PPC_ADV_DEBUG_REGS */
 
-               if (!access_ok(VERIFY_WRITE, datavp,
-                              sizeof(struct ppc_debug_info)))
+               if (copy_to_user(datavp, &dbginfo,
+                                sizeof(struct ppc_debug_info)))
                        return -EFAULT;
-               ret = __copy_to_user(datavp, &dbginfo,
-                                    sizeof(struct ppc_debug_info)) ?
-                     -EFAULT : 0;
-               break;
+               return 0;
        }
 
        case PPC_PTRACE_SETHWDEBUG: {
                struct ppc_hw_breakpoint bp_info;
 
-               if (!access_ok(VERIFY_READ, datavp,
-                              sizeof(struct ppc_hw_breakpoint)))
+               if (copy_from_user(&bp_info, datavp,
+                                  sizeof(struct ppc_hw_breakpoint)))
                        return -EFAULT;
-               ret = __copy_from_user(&bp_info, datavp,
-                                      sizeof(struct ppc_hw_breakpoint)) ?
-                     -EFAULT : 0;
-               if (!ret)
-                       ret = ppc_set_hwdebug(child, &bp_info);
-               break;
+               return ppc_set_hwdebug(child, &bp_info);
        }
 
        case PPC_PTRACE_DELHWDEBUG: {
-- 
2.14.1