x86/fpu: Eliminate the 'xfeatures' local variable in copy_user_to_xstate() (3d703477) · Commits · 戴 / test

We now have this field in hdr.xfeatures. 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/20170924105913.9157-9-mingo@kernel.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/fpu/xstate.c

+4 −7

Original line number	Diff line number	Diff line
		@@ -1197,7 +1197,6 @@ int copy_user_to_xstate(struct xregs_state xsave, const void __user ubuf)
		{
		unsigned int offset, size;
		int i;
		u64 xfeatures;
		u64 allowed_features;
		struct xstate_header hdr;

		@@ -1207,20 +1206,18 @@ int copy_user_to_xstate(struct xregs_state xsave, const void __user ubuf)
		if (__copy_from_user(&hdr, ubuf + offset, size))
		return -EFAULT;

		xfeatures = hdr.xfeatures;

		/*
		* Reject if the user sets any disabled or supervisor features:
		*/
		allowed_features = xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR;

		if (xfeatures & ~allowed_features)
		if (hdr.xfeatures & ~allowed_features)
		return -EINVAL;

		for (i = 0; i < XFEATURE_MAX; i++) {
		u64 mask = ((u64)1 << i);

		if (xfeatures & mask) {
		if (hdr.xfeatures & mask) {
		void *dst = __raw_xsave_addr(xsave, 1 << i);

		offset = xstate_offsets[i];
		@@ -1231,7 +1228,7 @@ int copy_user_to_xstate(struct xregs_state xsave, const void __user ubuf)
		}
		}

		if (xfeatures_mxcsr_quirk(xfeatures)) {
		if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
		offset = offsetof(struct fxregs_state, mxcsr);
		size = MXCSR_AND_FLAGS_SIZE;
		if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
		@@ -1247,7 +1244,7 @@ int copy_user_to_xstate(struct xregs_state xsave, const void __user ubuf)
		/*
		* Add back in the features that came in from userspace:
		*/
		xsave->header.xfeatures \|= xfeatures;
		xsave->header.xfeatures \|= hdr.xfeatures;

		return 0;
		}

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