From 993c670a4dfb2bded39d96f11df763c657d15a41 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Wed, 26 Feb 2020 03:35:35 +1000
Subject: [PATCH] powerpc/64/syscall: Zero volatile registers when returning
References: jsc#SLE-9246
Patch-mainline: v5.7-rc1
Git-commit: 993c670a4dfb2bded39d96f11df763c657d15a41
Kernel addresses and potentially other sensitive data could be leaked
in volatile registers after a syscall.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200225173541.1549955-27-npiggin@gmail.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/kernel/entry_64.S | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 5f70830b5ae4..29949bbe857b 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -141,6 +141,19 @@ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
cmpdi r3,0
bne .Lsyscall_restore_regs
+ /* Zero volatile regs that may contain sensitive kernel data */
+ li r0,0
+ li r4,0
+ li r5,0
+ li r6,0
+ li r7,0
+ li r8,0
+ li r9,0
+ li r10,0
+ li r11,0
+ li r12,0
+ mtctr r0
+ mtspr SPRN_XER,r0
.Lsyscall_restore_regs_cont:
BEGIN_FTR_SECTION
--
2.28.0