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boot: Refuse GPT with invalid entry size

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SizeOfPartitionEntry must be a multiple of 128 * 2^n.
This commit is contained in:
Jan Janssen 2022-08-29 10:09:01 +02:00
parent 71c628d426
commit 0cf5f816f2
1 changed files with 6 additions and 12 deletions
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18
src/boot/efi/xbootldr.c
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@ -67,7 +67,7 @@ static bool verify_gpt(union GptHeaderBuffer *gpt_header_buffer, EFI_LBA lba_exp
if (h->MyLBA != lba_expected)
return false;
if (h->SizeOfPartitionEntry < sizeof(EFI_PARTITION_ENTRY))
if ((h->SizeOfPartitionEntry % sizeof(EFI_PARTITION_ENTRY)) != 0)
return false;
if (h->NumberOfPartitionEntries <= 0 || h->NumberOfPartitionEntries > 1024)
@ -130,19 +130,13 @@ static EFI_STATUS try_gpt(
/* Now we can finally look for xbootloader partitions. */
for (UINTN i = 0; i < gpt.gpt_header.NumberOfPartitionEntries; i++) {
EFI_PARTITION_ENTRY *entry;
EFI_LBA start, end;
entry = (EFI_PARTITION_ENTRY*) ((uint8_t*) entries + gpt.gpt_header.SizeOfPartitionEntry * i);
EFI_PARTITION_ENTRY *entry =
(EFI_PARTITION_ENTRY *) ((uint8_t *) entries + gpt.gpt_header.SizeOfPartitionEntry * i);
if (memcmp(&entry->PartitionTypeGUID, XBOOTLDR_GUID, sizeof(entry->PartitionTypeGUID)) != 0)
continue;
/* Let's use memcpy(), in case the structs are not aligned (they really should be though) */
memcpy(&start, &entry->StartingLBA, sizeof(start));
memcpy(&end, &entry->EndingLBA, sizeof(end));
if (end < start) /* Bogus? */
if (entry->EndingLBA < entry->StartingLBA) /* Bogus? */
continue;
*ret_hd = (HARDDRIVE_DEVICE_PATH) {
@ -151,8 +145,8 @@ static EFI_STATUS try_gpt(
.SubType = MEDIA_HARDDRIVE_DP,
},
.PartitionNumber = i + 1,
.PartitionStart = start,
.PartitionSize = end - start + 1,
.PartitionStart = entry->StartingLBA,
.PartitionSize = entry->EndingLBA - entry->StartingLBA + 1,
.MBRType = MBR_TYPE_EFI_PARTITION_TABLE_HEADER,
.SignatureType = SIGNATURE_TYPE_GUID,
};