From: Jisheng Zhang jszhang@kernel.org
[ 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-n4Fr8O... 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 d7c6ca7c95ae..64180108072c 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -104,6 +104,8 @@ int copy_thread(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 */