[PATCH v3 2/5] lib: utils/irqchip: plic: Ensure no out-of-bound access in priority save/restore helpers

[Anup Patel]

On Sun, Dec 11, 2022 at 12:25 PM Bin Meng <bmeng at tinylab.org> wrote:
>
> Currently the priority save/restore helpers writes/reads the provided
> array using an index whose maximum value is determined by PLIC, which
> potentially may disagree with the caller to these helpers.
>
> Add a parameter to ask the caller to provide the size limit of the
> array to ensure no out-of-bound access happens.
>
> Signed-off-by: Bin Meng <bmeng at tinylab.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

>
> ---
>
> Changes in v3:
> - fix the size limit check
> - move the size limit check to plic_priority_save/restore
> - add parameter description to fdt_plic_priority_save/restore
>
> Changes in v2:
> - new patch: libs: utils/irqchip: plic: Ensure no out-of-bound access in priority save/restore helpers
>
>  include/sbi_utils/irqchip/fdt_irqchip_plic.h | 14 ++++++++++++--
>  include/sbi_utils/irqchip/plic.h             |  5 +++--
>  lib/utils/irqchip/fdt_irqchip_plic.c         |  8 ++++----
>  lib/utils/irqchip/plic.c                     | 15 +++++++++++----
>  platform/generic/allwinner/sun20i-d1.c       |  4 ++--
>  5 files changed, 32 insertions(+), 14 deletions(-)
>
> diff --git a/include/sbi_utils/irqchip/fdt_irqchip_plic.h b/include/sbi_utils/irqchip/fdt_irqchip_plic.h
> index 98d4de5..d5b1c60 100644
> --- a/include/sbi_utils/irqchip/fdt_irqchip_plic.h
> +++ b/include/sbi_utils/irqchip/fdt_irqchip_plic.h
> @@ -9,9 +9,19 @@
>
>  #include <sbi/sbi_types.h>
>
> -void fdt_plic_priority_save(u8 *priority);
> +/**
> + * Save the PLIC priority state
> + * @param priority pointer to the memory region for the saved priority
> + * @param num size of the memory region including interrupt source 0
> + */
> +void fdt_plic_priority_save(u8 *priority, u32 num);
>
> -void fdt_plic_priority_restore(const u8 *priority);
> +/**
> + * Restore the PLIC priority state
> + * @param priority pointer to the memory region for the saved priority
> + * @param num size of the memory region including interrupt source 0
> + */
> +void fdt_plic_priority_restore(const u8 *priority, u32 num);
>
>  void fdt_plic_context_save(bool smode, u32 *enable, u32 *threshold);
>
> diff --git a/include/sbi_utils/irqchip/plic.h b/include/sbi_utils/irqchip/plic.h
> index 48c24f0..38704a1 100644
> --- a/include/sbi_utils/irqchip/plic.h
> +++ b/include/sbi_utils/irqchip/plic.h
> @@ -18,9 +18,10 @@ struct plic_data {
>  };
>
>  /* So far, priorities on all consumers of these functions fit in 8 bits. */
> -void plic_priority_save(const struct plic_data *plic, u8 *priority);
> +void plic_priority_save(const struct plic_data *plic, u8 *priority, u32 num);
>
> -void plic_priority_restore(const struct plic_data *plic, const u8 *priority);
> +void plic_priority_restore(const struct plic_data *plic, const u8 *priority,
> +                          u32 num);
>
>  void plic_context_save(const struct plic_data *plic, int context_id,
>                        u32 *enable, u32 *threshold);
> diff --git a/lib/utils/irqchip/fdt_irqchip_plic.c b/lib/utils/irqchip/fdt_irqchip_plic.c
> index fe08836..7d76c5b 100644
> --- a/lib/utils/irqchip/fdt_irqchip_plic.c
> +++ b/lib/utils/irqchip/fdt_irqchip_plic.c
> @@ -24,18 +24,18 @@ static struct plic_data plic[PLIC_MAX_NR];
>  static struct plic_data *plic_hartid2data[SBI_HARTMASK_MAX_BITS];
>  static int plic_hartid2context[SBI_HARTMASK_MAX_BITS][2];
>
> -void fdt_plic_priority_save(u8 *priority)
> +void fdt_plic_priority_save(u8 *priority, u32 num)
>  {
>         struct plic_data *plic = plic_hartid2data[current_hartid()];
>
> -       plic_priority_save(plic, priority);
> +       plic_priority_save(plic, priority, num);
>  }
>
> -void fdt_plic_priority_restore(const u8 *priority)
> +void fdt_plic_priority_restore(const u8 *priority, u32 num)
>  {
>         struct plic_data *plic = plic_hartid2data[current_hartid()];
>
> -       plic_priority_restore(plic, priority);
> +       plic_priority_restore(plic, priority, num);
>  }
>
>  void fdt_plic_context_save(bool smode, u32 *enable, u32 *threshold)
> diff --git a/lib/utils/irqchip/plic.c b/lib/utils/irqchip/plic.c
> index 4df9020..dca5678 100644
> --- a/lib/utils/irqchip/plic.c
> +++ b/lib/utils/irqchip/plic.c
> @@ -36,15 +36,22 @@ static void plic_set_priority(const struct plic_data *plic, u32 source, u32 val)
>         writel(val, plic_priority);
>  }
>
> -void plic_priority_save(const struct plic_data *plic, u8 *priority)
> +void plic_priority_save(const struct plic_data *plic, u8 *priority, u32 num)
>  {
> -       for (u32 i = 1; i <= plic->num_src; i++)
> +       if (num > plic->num_src)
> +               num = plic->num_src;
> +
> +       for (u32 i = 1; i <= num; i++)
>                 priority[i] = plic_get_priority(plic, i);
>  }
>
> -void plic_priority_restore(const struct plic_data *plic, const u8 *priority)
> +void plic_priority_restore(const struct plic_data *plic, const u8 *priority,
> +                          u32 num)
>  {
> -       for (u32 i = 1; i <= plic->num_src; i++)
> +       if (num > plic->num_src)
> +               num = plic->num_src;
> +
> +       for (u32 i = 1; i <= num; i++)
>                 plic_set_priority(plic, i, priority[i]);
>  }
>
> diff --git a/platform/generic/allwinner/sun20i-d1.c b/platform/generic/allwinner/sun20i-d1.c
> index 18d330d..1f27575 100644
> --- a/platform/generic/allwinner/sun20i-d1.c
> +++ b/platform/generic/allwinner/sun20i-d1.c
> @@ -79,13 +79,13 @@ static u32 plic_threshold;
>  static void sun20i_d1_plic_save(void)
>  {
>         fdt_plic_context_save(true, plic_sie, &plic_threshold);
> -       fdt_plic_priority_save(plic_priority);
> +       fdt_plic_priority_save(plic_priority, PLIC_SOURCES);
>  }
>
>  static void sun20i_d1_plic_restore(void)
>  {
>         thead_plic_restore();
> -       fdt_plic_priority_restore(plic_priority);
> +       fdt_plic_priority_restore(plic_priority, PLIC_SOURCES);
>         fdt_plic_context_restore(true, plic_sie, plic_threshold);
>  }
>
> --
> 2.34.1
>
>
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