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Subject[PATCH 02/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in xstateregs_set()
Date
From: Eric Biggers <ebiggers@google.com>

Tighten the checks in xstateregs_set().

Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Hao <haokexin@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: kernel-hardening@lists.openwall.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/fpu/regset.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index ee8d2f049818..b831d5b9de99 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -141,27 +141,20 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
ret = copy_user_to_xstate(xsave, ubuf);
} else {
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
-
- /* xcomp_bv must be 0 when using uncompacted format */
- if (!ret && xsave->header.xcomp_bv)
- ret = -EINVAL;
+ if (!ret)
+ ret = validate_xstate_header(&xsave->header);
}

/*
- * In case of failure, mark all states as init:
- */
- if (ret)
- fpstate_init(&fpu->state);
-
- /*
* mxcsr reserved bits must be masked to zero for security reasons.
*/
xsave->i387.mxcsr &= mxcsr_feature_mask;
- xsave->header.xfeatures &= xfeatures_mask;
+
/*
- * These bits must be zero.
+ * In case of failure, mark all states as init:
*/
- memset(&xsave->header.reserved, 0, 48);
+ if (ret)
+ fpstate_init(&fpu->state);

return ret;
}
--
2.11.0
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