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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2019-04-03 18:41:30 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2019-04-09 19:27:29 +0200 |
| commit | 39ea9baffda91df8bfee9b45610242a3191ea1ec (patch) | |
| tree | 5a5a250a43b14094afd5920d286ede9a3c7b90a1 /arch/x86/kernel/fpu/regset.c | |
| parent | x86/fpu: Fix __user annotations (diff) | |
| download | linux-39ea9baffda91df8bfee9b45610242a3191ea1ec.tar.gz linux-39ea9baffda91df8bfee9b45610242a3191ea1ec.zip | |
x86/fpu: Remove fpu->initialized usage in __fpu__restore_sig()
This is a preparation for the removal of the ->initialized member in the
fpu struct.
__fpu__restore_sig() is deactivating the FPU via fpu__drop() and then
setting manually ->initialized followed by fpu__restore(). The result is
that it is possible to manipulate fpu->state and the state of registers
won't be saved/restored on a context switch which would overwrite
fpu->state:
fpu__drop(fpu):
...
fpu->initialized = 0;
preempt_enable();
<--- context switch
Don't access the fpu->state while the content is read from user space
and examined/sanitized. Use a temporary kmalloc() buffer for the
preparation of the FPU registers and once the state is considered okay,
load it. Should something go wrong, return with an error and without
altering the original FPU registers.
The removal of fpu__initialize() is a nop because fpu->initialized is
already set for the user task.
[ bp: Massage a bit. ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190403164156.19645-2-bigeasy@linutronix.de
Diffstat (limited to 'arch/x86/kernel/fpu/regset.c')
| -rw-r--r-- | arch/x86/kernel/fpu/regset.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c index bc02f5144b95..5dbc099178a8 100644 --- a/arch/x86/kernel/fpu/regset.c +++ b/arch/x86/kernel/fpu/regset.c @@ -269,11 +269,10 @@ convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk) memcpy(&to[i], &from[i], sizeof(to[0])); } -void convert_to_fxsr(struct task_struct *tsk, +void convert_to_fxsr(struct fxregs_state *fxsave, const struct user_i387_ia32_struct *env) { - struct fxregs_state *fxsave = &tsk->thread.fpu.state.fxsave; struct _fpreg *from = (struct _fpreg *) &env->st_space[0]; struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0]; int i; @@ -350,7 +349,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset, ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1); if (!ret) - convert_to_fxsr(target, &env); + convert_to_fxsr(&target->thread.fpu.state.fxsave, &env); /* * update the header bit in the xsave header, indicating the |