linux-kernel - [PATCH 5.4 68/90] x86/fpu: Reset state for all signal restore failures

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Message-Id: <20210621154906.462940408@linuxfoundation.org>
Date:   Mon, 21 Jun 2021 18:15:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...e.de>
Subject: [PATCH 5.4 68/90] x86/fpu: Reset state for all signal restore failures

From: Thomas Gleixner <tglx@...utronix.de>

commit efa165504943f2128d50f63de0c02faf6dcceb0d 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: 72a671ced66d ("x86, fpu: Unify signal handling code paths for x86 and x86_64 kernels")
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/87mtryyhhz.ffs@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/fpu/signal.c |   26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -289,13 +289,17 @@ static int __fpu__restore_sig(void __use
 		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;
@@ -333,7 +337,7 @@ static int __fpu__restore_sig(void __use
 	if (ia32_fxstate) {
 		ret = __copy_from_user(&env, buf, sizeof(env));
 		if (ret)
-			goto err_out;
+			goto out;
 		envp = &env;
 	} else {
 		/*
@@ -369,7 +373,7 @@ static int __fpu__restore_sig(void __use
 				ret = validate_xstate_header(&fpu->state.xsave.header);
 		}
 		if (ret)
-			goto err_out;
+			goto out;
 
 		sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
 
@@ -382,7 +386,7 @@ static int __fpu__restore_sig(void __use
 		ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
 		if (ret) {
 			ret = -EFAULT;
-			goto err_out;
+			goto out;
 		}
 
 		sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
@@ -397,7 +401,7 @@ static int __fpu__restore_sig(void __use
 	} 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);
@@ -408,7 +412,7 @@ static int __fpu__restore_sig(void __use
 		fpregs_deactivate(fpu);
 	fpregs_unlock();
 
-err_out:
+out:
 	if (ret)
 		fpu__clear(fpu);
 	return ret;