From 993c670a4dfb2bded39d96f11df763c657d15a41 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 26 Feb 2020 03:35:35 +1000 Subject: [PATCH] powerpc/64/syscall: Zero volatile registers when returning Kernel addresses and potentially other sensitive data could be leaked in volatile registers after a syscall. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200225173541.1549955-27-npiggin@gmail.com --- 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 -- 2.11.0