Messages in this thread Patch in this message | | | Date | Fri, 26 Aug 2011 14:58:31 -0700 | From | Greg KH <> | Subject | [10/19] fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops |
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2.6.32-longterm review patch. If anyone has any objections, please let us know.
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From: Timo Warns <Warns@pre-sense.de>
commit 3eb8e74ec72736b9b9d728bad30484ec89c91dde upstream.
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.
[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> [dannf: backported to Debian's 2.6.32] Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/partitions/efi.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/fs/partitions/efi.c +++ b/fs/partitions/efi.c @@ -311,6 +311,15 @@ is_gpt_valid(struct block_device *bdev, goto fail; } + /* Check the GUID Partition Table header size */ + if (le32_to_cpu((*gpt)->header_size) > + bdev_logical_block_size(bdev)) { + pr_debug("GUID Partition Table Header size is wrong: %u > %u\n", + le32_to_cpu((*gpt)->header_size), + bdev_logical_block_size(bdev)); + goto fail; + } + /* Check the GUID Partition Table CRC */ origcrc = le32_to_cpu((*gpt)->header_crc32); (*gpt)->header_crc32 = 0;
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