[PATCH] ARM: start: check for machine type last

[PATCH] ARM: start: check for machine type last

[Lucas Stach]

A valid DTB may reside low in the Barebox binary address map. If this
binary is started at a very low address, we might mistake the pointer
for a machine type. Make sure to check for all other possibilities first
before interpreting the boarddata as a raw machine type.

Fixes: 19c24e2f0121 (ARM: start: Allow to pass machine type as boarddata)
Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
 arch/arm/cpu/start.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index 44d974e40ef2..d99dd147b004 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -193,7 +193,17 @@ __noreturn void barebox_non_pbl_start(unsigned long membase,
 		uint32_t totalsize = 0;
 		const char *name;
 
-		if ((unsigned long)boarddata < 8192) {
+		if (blob_is_fdt(boarddata)) {
+			totalsize = get_unaligned_be32(boarddata + 4);
+			name = "DTB";
+		} else if (blob_is_compressed_fdt(boarddata)) {
+			struct barebox_arm_boarddata_compressed_dtb *bd = boarddata;
+			totalsize = bd->datalen + sizeof(*bd);
+			name = "Compressed DTB";
+		} else if (blob_is_arm_boarddata(boarddata)) {
+			totalsize = sizeof(struct barebox_arm_boarddata);
+			name = "machine type";
+		} else if ((unsigned long)boarddata < 8192) {
 			struct barebox_arm_boarddata *bd;
 			uint32_t machine_type = (unsigned long)boarddata;
 			unsigned long mem = arm_mem_boarddata(membase, endmem,
@@ -205,16 +215,6 @@ __noreturn void barebox_non_pbl_start(unsigned long membase,
 			bd->magic = BAREBOX_ARM_BOARDDATA_MAGIC;
 			bd->machine = machine_type;
 			malloc_end = mem;
-		} else if (blob_is_fdt(boarddata)) {
-			totalsize = get_unaligned_be32(boarddata + 4);
-			name = "DTB";
-		} else if (blob_is_compressed_fdt(boarddata)) {
-			struct barebox_arm_boarddata_compressed_dtb *bd = boarddata;
-			totalsize = bd->datalen + sizeof(*bd);
-			name = "Compressed DTB";
-		} else if (blob_is_arm_boarddata(boarddata)) {
-			totalsize = sizeof(struct barebox_arm_boarddata);
-			name = "machine type";
 		}
 
 		if (totalsize) {
-- 
2.23.0


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Re: [PATCH] ARM: start: check for machine type last

[Sascha Hauer]

On Thu, Nov 07, 2019 at 09:12:56PM +0100, Lucas Stach wrote:
> A valid DTB may reside low in the Barebox binary address map. If this
> binary is started at a very low address, we might mistake the pointer
> for a machine type. Make sure to check for all other possibilities first
> before interpreting the boarddata as a raw machine type.
> 
> Fixes: 19c24e2f0121 (ARM: start: Allow to pass machine type as boarddata)
> Signed-off-by: Lucas Stach <dev@lynxeye.de>
> ---
>  arch/arm/cpu/start.c | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)

Applied, thanks

Sascha

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