efi/fdt: fix panic when no valid fdt found

setup_arch() would invoke efi_init()->efi_get_fdt_params(). If no
valid fdt found then initial_boot_params will be null. So we
should stop further fdt processing here. I encountered this
issue on risc-v.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Fixes: b91540d52a08b ("RISC-V: Add EFI runtime services")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/drivers/firmware/efi/fdtparams.c b/drivers/firmware/efi/fdtparams.c
index bb042ab..e901f85 100644 (file)
--- a/drivers/firmware/efi/fdtparams.c
+++ b/drivers/firmware/efi/fdtparams.c
@@ -98,6 +98,9 @@ u64 __init efi_get_fdt_params(struct efi_memory_map_data *mm)
        BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(name));
        BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(dt_params[0].params));
 
+       if (!fdt)
+               return 0;
+
        for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
                node = fdt_path_offset(fdt, dt_params[i].path);
                if (node < 0)