From c5c0b3167537793a7cf936fb240366eefd2fc7fb Mon Sep 17 00:00:00 2001
From: Jisheng Zhang <jszhang@kernel.org>
Date: Sat, 29 Oct 2022 19:34:50 +0800
Subject: [PATCH] riscv: process: fix kernel info leakage
[ Upstream commit 6510c78490c490a6636e48b61eeaa6fb65981f4b ]
thread_struct's s[12] may contain random kernel memory content, which
may be finally leaked to userspace. This is a security hole. Fix it
by clearing the s[12] array in thread_struct when fork.
As for kthread case, it's better to clear the s[12] array as well.
Fixes: 7db91e57a0ac ("RISC-V: Task implementation")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Tested-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20221029113450.4027-1-jszhang@kernel.org
Reviewed-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/CAJF2gTSdVyAaM12T%2B7kXAdRPGS4VyuO08X1c7paE-n4Fr8OtRA@mail.gmail.com/
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/riscv/kernel/process.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 330b34706aa0..9d4b4098874b 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -104,6 +104,8 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
{
struct pt_regs *childregs = task_pt_regs(p);
+ memset(&p->thread.s, 0, sizeof(p->thread.s));
+
/* p->thread holds context to be restored by __switch_to() */
if (unlikely(p->flags & PF_KTHREAD)) {
/* Kernel thread */