The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From efa165504943f2128d50f63de0c02faf6dcceb0d Mon Sep 17 00:00:00 2001

From: Thomas Gleixner tglx@linutronix.de Date: Wed, 9 Jun 2021 21:18:00 +0200 Subject: [PATCH] x86/fpu: Reset state for all signal restore failures

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@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

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 4ab9aeb9a963..ec3ae3054792 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/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;