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gpt: fix partition table indexing and validation

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Portions of the code attempted to handle the fact that GPT entries on
disk may be larger than the currently defined struct while others
assumed the data could be indexed by the struct size directly. This
never came up because no utility uses a size larger than 128 bytes but
for the sake of safety we need to do this by the spec.
This commit is contained in:
Michael Marineau 2016-08-24 16:14:20 -07:00
parent 87dfbf34c4
commit bf127238ee
4 changed files with 176 additions and 12 deletions
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11
include/grub/gpt_partition.h
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@ -186,8 +186,10 @@ struct grub_gpt
struct grub_gpt_header primary;
struct grub_gpt_header backup;
/* Only need one entries table, on disk both copies are identical. */
struct grub_gpt_partentry *entries;
/* Only need one entries table, on disk both copies are identical.
* The on disk entry size may be larger than our partentry struct so
* the table cannot be indexed directly. */
void *entries;
grub_size_t entries_size;
/* Logarithm of sector size, in case GPT and disk driver disagree. */
@ -205,6 +207,11 @@ grub_gpt_sector_to_addr (grub_gpt_t gpt, grub_uint64_t sector)
/* Allocates and fills new grub_gpt structure, free with grub_gpt_free. */
grub_gpt_t grub_gpt_read (grub_disk_t disk);
/* Helper for indexing into the entries table.
* Returns NULL when the end of the table has been reached. */
struct grub_gpt_partentry * grub_gpt_get_partentry (grub_gpt_t gpt,
grub_uint32_t n);
/* Sync up primary and backup headers, recompute checksums. */
grub_err_t grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt);