um: don't rely on sc.fpstate not having been reassigned prior to rt_sigreturn()

native rt_sigreturn() doesn't...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 8 insertions, 5 deletions

diff --git a/arch/um/sys-x86_64/signal.c b/arch/um/sys-x86_64/signal.c
index 581b64d86a6c..ccfa5544e92c 100644
--- a/arch/um/sys-x86_64/signal.c
+++ b/arch/um/sys-x86_64/signal.c
@@ -44,10 +44,10 @@ void copy_sc(struct uml_pt_regs *regs, void *from)
 }
 
 static int copy_sc_from_user(struct pt_regs *regs,
-                             struct sigcontext __user *from,
-                             struct _fpstate __user *fpp)
+                             struct sigcontext __user *from)
 {
         struct user_i387_struct fp;
+        void __user *buf;
         int err = 0;
 
 #define GETREG(regs, regno, sc, regname)                                \
@@ -78,7 +78,11 @@ static int copy_sc_from_user(struct pt_regs *regs,
 
 #undef GETREG
 
-        err = copy_from_user(&fp, fpp, sizeof(struct user_i387_struct));
+        err = __get_user(buf, &from->fpstate);
+        if (err)
+                return 1;
+
+        err = copy_from_user(&fp, buf, sizeof(struct user_i387_struct));
         if (err)
                 return 1;
 
@@ -272,8 +276,7 @@ long sys_rt_sigreturn(struct pt_regs *regs)
         sigdelsetmask(&set, ~_BLOCKABLE);
         set_current_blocked(&set);
 
-        if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext,
-                              &frame->fpstate))
+        if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
                 goto segfault;
 
         /* Avoid ERESTART handling */