This is a note to let you know that I've just added the patch titled
x86/fpu: Fix the init_fpstate size check with the actual size
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-fpu-fix-the-init_fpstate-size-check-with-the-act.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 31435828c009f8de662aeb83f0b5ffe97de85d18
Author: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Date: Wed Aug 24 12:12:22 2022 -0700
x86/fpu: Fix the init_fpstate size check with the actual size
[ Upstream commit d3e021adac7c51a26d9ede167c789fcc1b878467 ]
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: 2ae996e0c1a3 ("x86/fpu: Calculate the default sizes independently")
Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220824191223.1248-3-chang.seok.bae@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index f0ce10620ab0..f5ef78633b4c 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -678,20 +678,6 @@ 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: */
@@ -717,10 +703,6 @@ 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;
@@ -879,6 +861,12 @@ 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();
/*
