From 79c5912e8d8748d5e36c7dc6376891c9f451e375 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Wed, 23 Aug 2017 16:01:33 +0200 Subject: [PATCH] part: efi: Disable overlap check The current code checks that no partitions overlap with the GPT partition table using the offset of the first LBA usable for that partition. This works fine, unless you have a partition entry that is further away than it usually is and you want to create partitions in the gap between the GPT header and the GPT partition entries, for example to reflash a bootloader that needs to be set there. Rework the test to something a bit smarter that checks whether a partition would overlap with either the GPT header or the partition entries, no matter where it is on the disk. Partitions that do not have a start LBA specified will still start at the first LBA usable set in the GPT header, to avoid weird behaviours. Signed-off-by: Maxime Ripard Reviewed-by: Tom Rini --- disk/part_efi.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/disk/part_efi.c b/disk/part_efi.c index 807d01de39..2973d52f6a 100644 --- a/disk/part_efi.c +++ b/disk/part_efi.c @@ -445,24 +445,38 @@ int gpt_fill_pte(struct blk_desc *dev_desc, char *str_type_guid; unsigned char *bin_type_guid; #endif + size_t hdr_start = gpt_h->my_lba; + size_t hdr_end = hdr_start + 1; + + size_t pte_start = gpt_h->partition_entry_lba; + size_t pte_end = pte_start + + gpt_h->num_partition_entries * gpt_h->sizeof_partition_entry / + dev_desc->blksz; for (i = 0; i < parts; i++) { /* partition starting lba */ lbaint_t start = partitions[i].start; lbaint_t size = partitions[i].size; - if (start && (start < offset)) { - printf("Partition overlap\n"); - return -1; - } - if (start) { - gpt_e[i].starting_lba = cpu_to_le64(start); offset = start + size; } else { - gpt_e[i].starting_lba = cpu_to_le64(offset); + start = offset; offset += size; } + + /* + * If our partition overlaps with either the GPT + * header, or the partition entry, reject it. + */ + if (((start <= hdr_end && hdr_start <= (start + size)) || + (start <= pte_end && pte_start <= (start + size)))) { + printf("Partition overlap\n"); + return -1; + } + + gpt_e[i].starting_lba = cpu_to_le64(start); + if (offset > (last_usable_lba + 1)) { printf("Partitions layout exceds disk size\n"); return -1; -- 2.39.5