fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops
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").
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.
[akpm@linux-foundation.org: fix layout and indenting] Signed-off-by: Timo Warns <warns@pre-sense.de> Cc: Matt Domsch <Matt_Domsch@dell.com> Cc: Eugene Teo <eugeneteo@kernel.sg> Cc: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>