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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@google.com>
AuthorDate: Sun, 24 Sep 2017 12:59:09 +0200
Committer: Ingo Molnar <mingo@kernel.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@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers3@gmail.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
Link: http://lkml.kernel.org/r/20170924105913.9157-7-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.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++) {
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