Commit-ID: aab8445c4e1cceeb3f739352041ec1c2586bc923 Gitweb: https://git.kernel.org/tip/aab8445c4e1cceeb3f739352041ec1c2586bc923 Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> AuthorDate: Fri, 7 Jun 2019 16:29:16 +0200 Committer: Borislav Petkov <bp@xxxxxxx> 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 <ebiggers@xxxxxxxxxx> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Tested-by: Eric Biggers <ebiggers@xxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: "Jason A. Donenfeld" <Jason@xxxxxxxxx> Cc: kvm ML <kvm@xxxxxxxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: x86-ml <x86@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20190607142915.y52mfmgk5lvhll7n@xxxxxxxxxxxxx --- 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)) ||
