Commit-ID: aab8445c4e1cceeb3f739352041ec1c2586bc923
Gitweb: https://git.kernel.org/tip/aab8445c4e1cceeb3f739352041ec1c2586bc923
Author: Sebastian Andrzej Siewior <bige...@linutronix.de>
AuthorDate: Fri, 7 Jun 2019 16:29:16 +0200
Committer: Borislav Petkov <b...@suse.de>
CommitDate: Sat, 8 Jun 2019 11:45:15 +0200
x86/fpu: Update kernel's FPU state before using for the fsave header
In commit
39388e80f9b0c ("x86/fpu: Don't save fxregs for ia32 frames in
copy_fpstate_to_sigframe()")
I removed the statement
| if (ia32_fxstate)
| copy_fxregs_to_kernel(fpu);
and argued that it was wrongly merged because the content was already
saved in kernel's state.
This was wrong: It is required to write it back because it is only
saved on the user-stack and save_fsave_header() reads it from task's
FPU-state. I missed that part…
Save x87 FPU state unless thread's FPU registers are already up to date.
Fixes: 39388e80f9b0c ("x86/fpu: Don't save fxregs for ia32 frames in
copy_fpstate_to_sigframe()")
Reported-by: Eric Biggers <ebigg...@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Signed-off-by: Borislav Petkov <b...@suse.de>
Tested-by: Eric Biggers <ebigg...@kernel.org>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Dave Hansen <dave.han...@intel.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Hugh Dickins <hu...@google.com>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Jann Horn <ja...@google.com>
Cc: "Jason A. Donenfeld" <ja...@zx2c4.com>
Cc: kvm ML <k...@vger.kernel.org>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Radim Krčmář <rkrc...@redhat.com>
Cc: Rik van Riel <r...@surriel.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: x86-ml <x...@kernel.org>
Link: https://lkml.kernel.org/r/20190607142915.y52mfmgk5lvhl...@linutronix.de
---
arch/x86/kernel/fpu/signal.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 060d6188b453..0071b794ed19 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -62,6 +62,11 @@ static inline int save_fsave_header(struct task_struct *tsk,
void __user *buf)
struct user_i387_ia32_struct env;
struct _fpstate_32 __user *fp = buf;
+ fpregs_lock();
+ if (!test_thread_flag(TIF_NEED_FPU_LOAD))
+ copy_fxregs_to_kernel(&tsk->thread.fpu);
+ fpregs_unlock();
+
convert_from_fxsr(&env, tsk);
if (__copy_to_user(buf, &env, sizeof(env)) ||
