Obvious sanity checks have been added for GPT entries.
GPT entries should not:
- collide with GPT header
- collide with GPT partitions
- override the disk size
These checks also ensure GPT entries are not too large.
Signed-off-by: Eugene Korenevsky <ekorenev...@gmail.com>
---
block/partitions/efi.c | 61 +++++++++++++++++++++++++++++++++++-------
1 file changed, 51 insertions(+), 10 deletions(-)
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 39f70d968754..722117b32585 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -338,6 +338,24 @@ static gpt_header *alloc_read_gpt_header(struct
parsed_partitions *state,
return gpt;
}
+/**
+ * disk_regions_collide() - tests if two disk regions intersect or one region
+ * contains other
+ * @firstlba1: first LBA of the first region
+ * @lastlba1: last LBA of the first region
+ * @firstlba2: first LBA of the second region
+ * @lastlba2: last LBA of the second region
+ */
+static bool disk_regions_collide(u64 firstlba1, u64 lastlba1,
+ u64 firstlba2, u64 lastlba2)
+{
+ if (lastlba1 < firstlba2)
+ return false;
+ if (lastlba2 < firstlba1)
+ return false;
+ return true;
+}
+
/**
* is_gpt_valid() - tests one GPT header and PTEs for validity
* @state: disk parsed partitions
@@ -352,7 +370,8 @@ static int is_gpt_valid(struct parsed_partitions *state,
u64 lba,
gpt_header **gpt, gpt_entry **ptes)
{
u32 crc, origcrc;
- u64 lastlba, pt_size;
+ unsigned short ssz;
+ u64 pt_firstlba, pt_lastlba, disk_lastlba, pt_size;
if (!ptes)
return 0;
@@ -369,11 +388,10 @@ static int is_gpt_valid(struct parsed_partitions *state,
u64 lba,
}
/* Check the GUID Partition Table header size is too big */
- if (le32_to_cpu((*gpt)->header_size) >
- bdev_logical_block_size(state->bdev)) {
+ ssz = bdev_logical_block_size(state->bdev);
+ if (le32_to_cpu((*gpt)->header_size) > ssz) {
pr_debug("GUID Partition Table Header size is too large: %u >
%u\n",
- le32_to_cpu((*gpt)->header_size),
- bdev_logical_block_size(state->bdev));
+ le32_to_cpu((*gpt)->header_size), ssz);
goto fail;
}
@@ -409,17 +427,17 @@ static int is_gpt_valid(struct parsed_partitions *state,
u64 lba,
/* Check the first_usable_lba and last_usable_lba are
* within the disk.
*/
- lastlba = last_lba(state->bdev);
- if (le64_to_cpu((*gpt)->first_usable_lba) > lastlba) {
+ disk_lastlba = last_lba(state->bdev);
+ if (le64_to_cpu((*gpt)->first_usable_lba) > disk_lastlba) {
pr_debug("GPT: first_usable_lba incorrect: %lld > %lld\n",
(unsigned long
long)le64_to_cpu((*gpt)->first_usable_lba),
- (unsigned long long)lastlba);
+ (unsigned long long)disk_lastlba);
goto fail;
}
- if (le64_to_cpu((*gpt)->last_usable_lba) > lastlba) {
+ if (le64_to_cpu((*gpt)->last_usable_lba) > disk_lastlba) {
pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
(unsigned long
long)le64_to_cpu((*gpt)->last_usable_lba),
- (unsigned long long)lastlba);
+ (unsigned long long)disk_lastlba);
goto fail;
}
if (le64_to_cpu((*gpt)->last_usable_lba) <
le64_to_cpu((*gpt)->first_usable_lba)) {
@@ -443,6 +461,29 @@ static int is_gpt_valid(struct parsed_partitions *state,
u64 lba,
goto fail;
}
+ pt_firstlba = le64_to_cpu((*gpt)->partition_entry_lba);
+ pt_lastlba = pt_firstlba + (pt_size + ssz - 1) / ssz - 1;
+
+ /* Check GPT entries do not overwrite partitions */
+ if (disk_regions_collide(pt_firstlba, pt_lastlba,
+ le64_to_cpu((*gpt)->first_usable_lba),
+ le64_to_cpu((*gpt)->last_usable_lba))) {
+ pr_debug("Primary GPT entries overwrite partitions\n");
+ goto fail;
+ }
+ /* Check GPT entries do not overwrite GPT header. Note: GPT header must
+ * reside in the single disk sector according to UEFI spec
+ */
+ if (disk_regions_collide(pt_firstlba, pt_lastlba, lba, lba)) {
+ pr_debug("Primary GPT entries overwrite GPT header\n");
+ goto fail;
+ }
+ /* Check GPT entries are not beyond the end of the disk */
+ if (pt_lastlba > disk_lastlba) {
+ pr_debug("GPT entries are beyond the end of the disk\n");
+ goto fail;
+ }
+
if (!(*ptes = alloc_read_gpt_entries(state, *gpt)))
goto fail;
--
2.19.1
