When barebox is started 2nd stage from another barebox or U-Boot it usually gets a device tree passed in a register. We can't rely on this though, so before assuming a pointer has a device tree we need to perform some basic checks for being in a certain range, is sufficiently aligned and actually contains a device tree. This adds a function performing these checks.
Signed-off-by: Sascha Hauer <[email protected]> --- include/compressed-dtb.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/include/compressed-dtb.h b/include/compressed-dtb.h index 3359d1ee11..cc5fbb2769 100644 --- a/include/compressed-dtb.h +++ b/include/compressed-dtb.h @@ -3,6 +3,7 @@ #define COMPRESSED_DTB_H_ #include <linux/types.h> +#include <linux/sizes.h> #include <asm/unaligned.h> struct barebox_boarddata_compressed_dtb { @@ -31,4 +32,27 @@ static inline bool blob_is_fdt(const void *blob) return get_unaligned_be32(blob) == FDT_MAGIC; } +static inline bool blob_is_valid_fdt_ptr(const void *blob, unsigned long mem_start, + unsigned long mem_size, unsigned int *fdt_size) +{ + unsigned long dtb = (unsigned long)blob; + unsigned int size; + + if (!IS_ALIGNED(dtb, 4)) + return false; + if (dtb < mem_start || dtb >= mem_start + mem_size) + return false; + if (!blob_is_fdt(blob)) + return false; + + size = be32_to_cpup(blob + 4); + if (size > SZ_2M || dtb + size > mem_start + mem_size) + return false; + + if (fdt_size) + *fdt_size = size; + + return true; +} + #endif -- 2.39.5
