Commit 0726e8b7 authored by Chang S. Bae's avatar Chang S. Bae Committed by Lin Wang
Browse files

x86/fpu: Fix the init_fpstate size check with the actual size 

mainline inclusion
from mainline-v6.1-rc2
commit d3e021ad
category: bugfix
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I73H0T
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d3e021adac7c51a26d9ede167c789fcc1b878467



Intel-SIG: commit d3e021ad x86/fpu: Fix the init_fpstate size check
with the actual size.

--------------------------------

The init_fpstate buffer is statically allocated. Thus, the sanity test was
established to check whether the pre-allocated buffer is enough for the
calculated size or not.

The currently measured size is not strictly relevant. Fix to validate the
calculated init_fpstate size with the pre-allocated area.

Also, replace the sanity check function with open code for clarity. The
abstraction itself and the function naming do not tend to represent simply
what it does.

Fixes: 2ae996e0 ("x86/fpu: Calculate the default sizes independently")
Signed-off-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220824191223.1248-3-chang.seok.bae@intel.com


Signed-off-by: default avatarLin Wang <lin.x.wang@intel.com>
parent 24ab4cb0

arch/x86/kernel/fpu/xstate.c

+6 −18
Original line number Diff line number Diff line
@@ -669,20 +669,6 @@ static unsigned int __init get_xsave_size_user(void) 
	return ebx;

}



/*

 * Will the runtime-enumerated 'xstate_size' fit in the init

 * task's statically-allocated buffer?

 */

static bool __init is_supported_xstate_size(unsigned int test_xstate_size)

{

	if (test_xstate_size <= sizeof(init_fpstate.regs))

		return true;



	pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",

			sizeof(init_fpstate.regs), test_xstate_size);

	return false;

}



static int __init init_xstate_size(void)

{

	/* Recompute the context size for enabled features: */
@@ -707,10 +693,6 @@ static int __init init_xstate_size(void) 
	kernel_default_size =

		xstate_calculate_size(fpu_kernel_cfg.default_features, compacted);



	/* Ensure we have the space to store all default enabled features. */

	if (!is_supported_xstate_size(kernel_default_size))

		return -EINVAL;



	if (!paranoid_xstate_size_valid(kernel_size))

		return -EINVAL;
@@ -861,6 +843,12 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) 
	init_fpstate.size		= fpu_kernel_cfg.max_size;

	init_fpstate.xfeatures		= fpu_kernel_cfg.max_features;



	if (init_fpstate.size > sizeof(init_fpstate.regs)) {

		pr_warn("x86/fpu: init_fpstate buffer too small (%zu < %d), disabling XSAVE\n",

			sizeof(init_fpstate.regs), init_fpstate.size);

		goto out_disable;

	}



	setup_init_fpu_buf();



	/*