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x86/fpu: Fail ptrace() requests that try to set invalid MXCSR values

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There is no benefit from accepting and silently changing an invalid MXCSR
value supplied via ptrace().  Instead, return -EINVAL on invalid input.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.613614842@linutronix.de
This commit is contained in:
Andy Lutomirski 2021-06-23 14:01:40 +02:00 committed by Borislav Petkov
parent 6164331d15
commit 145e9e0d8c
1 changed files with 3 additions and 2 deletions
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5
arch/x86/kernel/fpu/regset.c
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@ -63,8 +63,9 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
if (ret)
return ret;
/* Mask invalid MXCSR bits (for historical reasons). */
newstate.mxcsr &= mxcsr_feature_mask;
/* Do not allow an invalid MXCSR value. */
if (newstate.mxcsr & ~mxcsr_feature_mask)
return -EINVAL;
fpu__prepare_write(fpu);