linux-kernel - [tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the xstate_header in copy_kernel_to

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Message-ID: <tip-af95774b3ca080b0e1e651c0fc7680f3444ddda7@git.kernel.org>
Date:   Tue, 26 Sep 2017 01:36:20 -0700
From:   tip-bot for Eric Biggers <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, oleg@...hat.com, ebiggers3@...il.com,
        keescook@...omium.org, luto@...nel.org, yu-cheng.yu@...el.com,
        hpa@...or.com, dave.hansen@...ux.intel.com, haokexin@...il.com,
        peterz@...radead.org, akpm@...ux-foundation.org,
        mhalcrow@...gle.com, ebiggers@...gle.com, fenghua.yu@...el.com,
        torvalds@...ux-foundation.org, wanpeng.li@...mail.com,
        luto@...capital.net, dvyukov@...gle.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, bp@...en8.de, riel@...hat.com
Subject: [tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the
 xstate_header in copy_kernel_to_xstate()

Commit-ID:  af95774b3ca080b0e1e651c0fc7680f3444ddda7
Gitweb:     http://git.kernel.org/tip/af95774b3ca080b0e1e651c0fc7680f3444ddda7
Author:     Eric Biggers <ebiggers@...gle.com>
AuthorDate: Sun, 24 Sep 2017 12:59:09 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 26 Sep 2017 09:43:47 +0200

x86/fpu: Use validate_xstate_header() to validate the xstate_header in copy_kernel_to_xstate()

Tighten the checks in copy_kernel_to_xstate().

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Eric Biggers <ebiggers3@...il.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Kevin Hao <haokexin@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michael Halcrow <mhalcrow@...gle.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Cc: Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc: kernel-hardening@...ts.openwall.com
Link: http://lkml.kernel.org/r/20170924105913.9157-7-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/fpu/xstate.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c97c4a9..325db78 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1138,15 +1138,12 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
 
 /*
  * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format
- * and copy to the target thread. This is called from xstateregs_set() and
- * there we check the CPU has XSAVES and a whole standard-sized buffer
- * exists.
+ * and copy to the target thread. This is called from xstateregs_set().
  */
 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 {
 	unsigned int offset, size;
 	int i;
-	u64 allowed_features;
 	struct xstate_header hdr;
 
 	offset = offsetof(struct xregs_state, header);
@@ -1154,12 +1151,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 
 	memcpy(&hdr, kbuf + offset, size);
 
-	/*
-	 * Reject if the user sets any disabled or supervisor features:
-	 */
-	allowed_features = xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR;
-
-	if (hdr.xfeatures & ~allowed_features)
+	if (validate_xstate_header(&hdr))
 		return -EINVAL;
 
 	for (i = 0; i < XFEATURE_MAX; i++) {