2.6.33-longterm review patch. If anyone has any objections, please let us know.
------------------
From: Timo Warns <wa...@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.
[a...@linux-foundation.org: fix layout and indenting]
Signed-off-by: Timo Warns <wa...@pre-sense.de>
Cc: Matt Domsch <matt_dom...@dell.com>
Cc: Eugene Teo <eugene...@kernel.sg>
Cc: Dave Jones <da...@codemonkey.org.uk>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
[dannf: backported to Debian's 2.6.32]
Signed-off-by: Greg Kroah-Hartman <gre...@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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