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riscv: process: fix kernel info leakage

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[ 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>
This commit is contained in:
Jisheng Zhang 2022-10-29 19:34:50 +08:00 committed by Greg Kroah-Hartman
parent a8d67367ab
commit cc36c7fa5d
1 changed files with 2 additions and 0 deletions
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2
arch/riscv/kernel/process.c
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@ -124,6 +124,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
{
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 | PF_IO_WORKER))) {
/* Kernel thread */