[PATCH 5.17 1065/1126] x86/fpu/xstate: Fix the ARCH_REQ_XCOMP_PERM implementation

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 06:29:03 EST


From: Yang Zhong <yang.zhong@xxxxxxxxx>

commit 063452fd94d153d4eb38ad58f210f3d37a09cca4 upstream.

ARCH_REQ_XCOMP_PERM is supposed to add the requested feature to the
permission bitmap of thread_group_leader()->fpu. But the code overwrites
the bitmap with the requested feature bit only rather than adding it.

Fix the code to add the requested feature bit to the master bitmask.

Fixes: db8268df0983 ("x86/arch_prctl: Add controls for dynamic XSTATE components")
Signed-off-by: Yang Zhong <yang.zhong@xxxxxxxxx>
Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Paolo Bonzini <bonzini@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20220129173647.27981-2-chang.seok.bae@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/fpu/xstate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1639,7 +1639,7 @@ static int __xstate_request_perm(u64 per

perm = guest ? &fpu->guest_perm : &fpu->perm;
/* Pairs with the READ_ONCE() in xstate_get_group_perm() */
- WRITE_ONCE(perm->__state_perm, requested);
+ WRITE_ONCE(perm->__state_perm, mask);
/* Protected by sighand lock */
perm->__state_size = ksize;
perm->__user_state_size = usize;