x86/fpu: Reset state for all signal restore failures

commit efa1655 upstream.

If access_ok() or fpregs_soft_set() fails in __fpu__restore_sig() then the
function just returns but does not clear the FPU state as it does for all
other fatal failures.

Clear the FPU state for these failures as well.

Fixes: 72a671c ("x86, fpu: Unify signal handling code paths for x86 and x86_64 kernels")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/87mtryyhhz.ffs@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/x86/kernel/fpu/signal.c

@@ -307,13 +307,17 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 		return 0;
 	}
 
-	if (!access_ok(buf, size))
-		return -EACCES;
+	if (!access_ok(buf, size)) {
+		ret = -EACCES;
+		goto out;
+	}
 
-	if (!static_cpu_has(X86_FEATURE_FPU))
-		return fpregs_soft_set(current, NULL,
-				       0, sizeof(struct user_i387_ia32_struct),
-				       NULL, buf) != 0;
+	if (!static_cpu_has(X86_FEATURE_FPU)) {
+		ret = fpregs_soft_set(current, NULL, 0,
+				      sizeof(struct user_i387_ia32_struct),
+				      NULL, buf);
+		goto out;
+	}
 
 	if (use_xsave()) {
 		struct _fpx_sw_bytes fx_sw_user;
@@ -396,7 +400,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 		 */
 		ret = __copy_from_user(&env, buf, sizeof(env));
 		if (ret)
-			goto err_out;
+			goto out;
 		envp = &env;
 	}
 
@@ -426,7 +430,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 
 		ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
 		if (ret)
-			goto err_out;
+			goto out;
 
 		sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
 					      fx_only);
@@ -446,7 +450,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 		ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
 		if (ret) {
 			ret = -EFAULT;
-			goto err_out;
+			goto out;
 		}
 
 		sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
@@ -464,7 +468,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 	} else {
 		ret = __copy_from_user(&fpu->state.fsave, buf_fx, state_size);
 		if (ret)
-			goto err_out;
+			goto out;
 
 		fpregs_lock();
 		ret = copy_kernel_to_fregs_err(&fpu->state.fsave);
@@ -475,7 +479,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 		fpregs_deactivate(fpu);
 	fpregs_unlock();
 
-err_out:
+out:
 	if (ret)
 		fpu__clear_user_states(fpu);
 	return ret;