linux-kernel - [PATCH] of/kexec: Fix reading 32-bit "linux,initrd-{start,end}" values

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Date:   Mon, 28 Nov 2022 14:24:39 -0600
From:   Rob Herring <robh@...nel.org>
To:     Frank Rowand <frowand.list@...il.com>
Cc:     Peter Maydell <peter.maydell@...aro.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] of/kexec: Fix reading 32-bit "linux,initrd-{start,end}" values

"linux,initrd-start" and "linux,initrd-end" can be 32-bit values even on
a 64-bit platform. Ideally, the size should be based on
'#address-cells', but that has never been enforced in the kernel's FDT
boot parsing code (early_init_dt_check_for_initrd()). Bootloader
behavior is known to vary. For example, kexec always writes these as
64-bit.

Use of_read_number() to mirror the early_init_dt_check_for_initrd()
code.

Reported-by: Peter Maydell <peter.maydell@...aro.org>
Signed-off-by: Rob Herring <robh@...nel.org>
---
 drivers/of/kexec.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index e6c01db393f9..f26d2ba8a371 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -281,7 +281,7 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
 				   const char *cmdline, size_t extra_fdt_size)
 {
 	void *fdt;
-	int ret, chosen_node;
+	int ret, chosen_node, len;
 	const void *prop;
 	size_t fdt_size;
 
@@ -324,19 +324,19 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
 		goto out;
 
 	/* Did we boot using an initrd? */
-	prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
+	prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", &len);
 	if (prop) {
 		u64 tmp_start, tmp_end, tmp_size;
 
-		tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
+		tmp_start = of_read_number(prop, len / 4);
 
-		prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
+		prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", &len);
 		if (!prop) {
 			ret = -EINVAL;
 			goto out;
 		}
 
-		tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
+		tmp_end = of_read_number(prop, len / 4);
 
 		/*
 		 * kexec reserves exact initrd size, while firmware may
-- 
2.35.1