Re: [PATCH v3 3/3] LoongArch: Avoid initrd overlap during kernel relocation

[Huacai Chen]

Hi, Rui,

On Wed, Apr 29, 2026 at 1:14 PM WANG Rui <r@xxxxxx> wrote:
>
> Validate the relocation address against the initrd region specified
> via "initrd=" or "initrdmem=" on the command line. Reject relocation
> targets that overlap the initrd to prevent memory corruption during
> early boot.
>
> Signed-off-by: WANG Rui <r@xxxxxx>
> ---
>  arch/loongarch/kernel/relocate.c | 45 ++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
>
> diff --git a/arch/loongarch/kernel/relocate.c b/arch/loongarch/kernel/relocate.c
> index c36604a81d08..c303c0be8f06 100644
> --- a/arch/loongarch/kernel/relocate.c
> +++ b/arch/loongarch/kernel/relocate.c
> @@ -214,14 +214,59 @@ static inline void __init *determine_relocation_address(void)
>         return RELOCATED_KASLR(destination);
>  }
>
> +static unsigned long __init try_get_initrd(unsigned long *size)
Rename to determine_initrd_address() can keep consistency.

> +{
> +       unsigned long start = 0;
> +       unsigned int key_length;
It's type should be "unsigned long" because strstr() returns "unsigned long".

Huacai

> +       const char *key;
> +       char *p;
> +
> +       key = "initrd=";
> +       key_length = strlen(key);
> +       p = strstr(boot_command_line, key);
> +
> +       if (!p) {
> +               key = "initrdmem=";
> +               key_length = strlen(key);
> +               p = strstr(boot_command_line, key);
> +       }
> +
> +       if (p == boot_command_line || (p > boot_command_line && *(p - 1) == ' ')) {
> +               char *endp;
> +
> +               p += key_length;
> +               start = memparse(p, &endp);
> +               if (*endp == ',')
> +                       *size = memparse(endp + 1, NULL);
> +       }
> +
> +       return start;
> +}
> +
>  static inline int __init relocation_addr_valid(void *location_new)
>  {
> +       unsigned long initrd_start;
> +       unsigned long initrd_size = 0;
> +
>         if ((unsigned long)location_new & 0x00000ffff)
>                 return 0; /* Inappropriately aligned new location */
>
>         if ((unsigned long)location_new < (unsigned long)_end)
>                 return 0; /* New location overlaps original kernel */
>
> +       initrd_start = try_get_initrd(&initrd_size);
> +       if (initrd_start && initrd_size) {
> +               unsigned long kernel_start;
> +               unsigned long kernel_size;
> +
> +               kernel_start = PHYSADDR(location_new);
> +               kernel_size = (unsigned long)_end - (unsigned long)_text;
> +
> +               if (kernel_start < (initrd_start + initrd_size) &&
> +                       initrd_start < (kernel_start + kernel_size))
> +                       return 0; /* Initrd overlaps kernel */
> +       }
> +
>         return 1;
>  }
>  #endif
> --
> 2.54.0
>