diff options
| author | Alden Tondettar | 2017-01-15 15:31:56 -0700 |
|---|---|---|
| committer | Jens Axboe | 2017-01-17 09:02:31 -0700 |
| commit | c5082b70adfe8e1ea1cf4a8eff92c9f260e364d2 (patch) | |
| tree | 2cc8bab578b10b57837d87d9ec274aa19af7b2a3 | |
| parent | 1e668f4e7921e8c82838cf5f95ff4a2d5c852efc (diff) | |
partitions/efi: Fix integer overflow in GPT size calculation
If a GUID Partition Table claims to have more than 2**25 entries, the
calculation of the partition table size in alloc_read_gpt_entries() will
overflow a 32-bit integer and not enough space will be allocated for the
table.
Nothing seems to get written out of bounds, but later efi_partition() will
read up to 32768 bytes from a 128 byte buffer, possibly OOPSing or exposing
information to /proc/partitions and uevents.
The problem exists on both 64-bit and 32-bit platforms.
Fix the overflow and also print a meaningful debug message if the table
size is too large.
Signed-off-by: Alden Tondettar <alden.tondettar@gmail.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
| -rw-r--r-- | block/partitions/efi.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/block/partitions/efi.c b/block/partitions/efi.c index bcd86e5cd546..39f70d968754 100644 --- a/block/partitions/efi.c +++ b/block/partitions/efi.c @@ -293,7 +293,7 @@ static gpt_entry *alloc_read_gpt_entries(struct parsed_partitions *state, if (!gpt) return NULL; - count = le32_to_cpu(gpt->num_partition_entries) * + count = (size_t)le32_to_cpu(gpt->num_partition_entries) * le32_to_cpu(gpt->sizeof_partition_entry); if (!count) return NULL; @@ -352,7 +352,7 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba, gpt_header **gpt, gpt_entry **ptes) { u32 crc, origcrc; - u64 lastlba; + u64 lastlba, pt_size; if (!ptes) return 0; @@ -434,13 +434,20 @@ static int is_gpt_valid(struct parsed_partitions *state, u64 lba, goto fail; } + /* Sanity check partition table size */ + pt_size = (u64)le32_to_cpu((*gpt)->num_partition_entries) * + le32_to_cpu((*gpt)->sizeof_partition_entry); + if (pt_size > KMALLOC_MAX_SIZE) { + pr_debug("GUID Partition Table is too large: %llu > %lu bytes\n", + (unsigned long long)pt_size, KMALLOC_MAX_SIZE); + goto fail; + } + if (!(*ptes = alloc_read_gpt_entries(state, *gpt))) goto fail; /* Check the GUID Partition Entry Array CRC */ - crc = efi_crc32((const unsigned char *) (*ptes), - le32_to_cpu((*gpt)->num_partition_entries) * - le32_to_cpu((*gpt)->sizeof_partition_entry)); + crc = efi_crc32((const unsigned char *) (*ptes), pt_size); if (crc != le32_to_cpu((*gpt)->partition_entry_array_crc32)) { pr_debug("GUID Partition Entry Array CRC check failed.\n"); |