From: Timo Warns Subject: fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops References: bnc#687113 CVE-2011-1577 Patch-mainline: Probably 2.6.39; In -mm already The kernel automatically evaluates partition tables of storage devices. The code for evaluating GUID partitions (in fs/partitions/efi.c) contains a bug that causes a kernel oops on certain corrupted GUID partition tables. This bug has security impacts, because it allows, for example, to prepare a storage device that crashes a kernel subsystem upon connecting the device (e.g., a "USB Stick of (Partial) Death"). crc = efi_crc32((const unsigned char *) (*gpt), le32_to_cpu((*gpt)->header_size)); computes a CRC32 checksum over gpt covering (*gpt)->header_size bytes. There is no validation of (*gpt)->header_size before the efi_crc32 call. A corrupted partition table may have large values for (*gpt)->header_size. In this case, the CRC32 computation access memory beyond the memory allocated for gpt, which may cause a kernel heap overflow. Validate value of GUID partition table header size. Signed-off-by: Timo Warns Cc: Matt Domsch Cc: Eugene Teo Cc: Dave Jones Signed-off-by: Andrew Morton Acked-by: Jeff Mahoney --- fs/partitions/efi.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/fs/partitions/efi.c +++ b/fs/partitions/efi.c @@ -310,6 +310,15 @@ static int is_gpt_valid(struct parsed_pa goto fail; } + /* Check the GUID Partition Table header size */ + if (le32_to_cpu((*gpt)->header_size) > + bdev_logical_block_size(state->bdev)) { + pr_debug("GUID Partition Table Header size is wrong: %u > %u\n", + le32_to_cpu((*gpt)->header_size), + bdev_logical_block_size(state->bdev)); + goto fail; + } + /* Check the GUID Partition Table CRC */ origcrc = le32_to_cpu((*gpt)->header_crc32); (*gpt)->header_crc32 = 0;