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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Changbin Du <changbin.du@gmail.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.12 007/161] efi/fdt: fix panic when no valid fdt found
Date:   Tue,  8 Jun 2021 20:25:37 +0200
Message-Id: <20210608175945.722088507@linuxfoundation.org>
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From: Changbin Du <changbin.du@gmail.com>

[ Upstream commit 668a84c1bfb2b3fd5a10847825a854d63fac7baa ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 bb042ab7c2be..e901f8564ca0 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)
-- 
2.30.2