[PATCH 02/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in xstateregs_set()

[Ingo Molnar]

From: Eric Biggers <ebiggers@xxxxxxxxxx>

Tighten the checks in xstateregs_set().

Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kevin Hao <haokexin@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Michael Halcrow <mhalcrow@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Cc: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: kernel-hardening@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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