[tip: efi/urgent] efi/fdt: fix panic when no valid fdt found

[tip-bot2 for Changbin Du]

The following commit has been merged into the efi/urgent branch of tip:

Commit-ID:     668a84c1bfb2b3fd5a10847825a854d63fac7baa
Gitweb:        https://git.kernel.org/tip/668a84c1bfb2b3fd5a10847825a854d63fac7baa
Author:        Changbin Du <changbin.du@xxxxxxxxx>
AuthorDate:    Wed, 24 Mar 2021 22:54:35 +08:00
Committer:     Ard Biesheuvel <ardb@xxxxxxxxxx>
CommitterDate: Sat, 22 May 2021 14:03:42 +02:00

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@xxxxxxxxx>
Fixes: b91540d52a08b ("RISC-V: Add EFI runtime services")
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
 drivers/firmware/efi/fdtparams.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/fdtparams.c b/drivers/firmware/efi/fdtparams.c
index bb042ab..e901f85 100644
--- 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)