[PATCH 5.12 146/178] x86/fpu: Reset state for all signal restore failures

Greg Kroah-Hartman
2021-06-21T16:49:34Z

From: Thomas Gleixner <tglx@linutronix.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@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 | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)

--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -307,13 +307,17 @@ 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;
@@ -396,7 +400,7 @@ static int __fpu__restore_sig(void __use
*/
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 __use

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 __use
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 __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);
@@ -475,7 +479,7 @@ static int __fpu__restore_sig(void __use
fpregs_deactivate(fpu);
fpregs_unlock();

-err_out:
+out:
if (ret)
fpu__clear_user_states(fpu);
return ret;