Messages in this thread | | | From | yunhui cui <> | Date | Wed, 27 Mar 2024 16:43:31 +0800 | Subject | Re: [External] [PATCH] riscv: process: Fix kernel gp leakage |
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Hi Stefan,
On Wed, Mar 27, 2024 at 2:14 PM Stefan O'Rear <sorear@fastmail.com> wrote: > > childregs represents the registers which are active for the new thread > in user context. For a kernel thread, childregs->gp is never used since > the kernel gp is not touched by switch_to. For a user mode helper, the > gp value can be observed in user space after execve or possibly by other > means. > > Fixes: 7db91e57a0ac ("RISC-V: Task implementation") > Signed-off-by: Stefan O'Rear <sorear@fastmail.com> > --- > arch/riscv/kernel/process.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c > index 92922dbd5b5c..51042f48da17 100644 > --- a/arch/riscv/kernel/process.c > +++ b/arch/riscv/kernel/process.c > @@ -27,8 +27,6 @@ > #include <asm/vector.h> > #include <asm/cpufeature.h> > > -register unsigned long gp_in_global __asm__("gp"); > - > #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK) > #include <linux/stackprotector.h> > unsigned long __stack_chk_guard __read_mostly; > @@ -207,7 +205,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) > if (unlikely(args->fn)) { > /* Kernel thread */ > memset(childregs, 0, sizeof(struct pt_regs)); > - childregs->gp = gp_in_global; > /* Supervisor/Machine, irqs on: */ > childregs->status = SR_PP | SR_PIE; > > -- > 2.40.1 > > Can you help express in more detail what the problem was before fixing it?
Thanks, Yunhui
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