Messages in this thread Patch in this message | | | From | Stefan O'Rear <> | Subject | [PATCH] riscv: process: Fix kernel gp leakage | Date | Wed, 27 Mar 2024 02:12:58 -0400 |
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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
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