lkml.org 
[lkml]   [2012]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[34-longterm 193/196] fs/partitions/efi.c: corrupted GUID partition tables can cause kernel oops
Date
From: Timo Warns <Warns@pre-sense.de>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.
-------------------

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]
[PG: replace state->bdev with bdev, since 1493bf217f7f isn't in 34]

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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
fs/partitions/efi.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/fs/partitions/efi.c b/fs/partitions/efi.c
index ee59684..9b40337 100644
--- a/fs/partitions/efi.c
+++ b/fs/partitions/efi.c
@@ -312,6 +312,15 @@ is_gpt_valid(struct block_device *bdev, u64 lba,
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;
--
1.7.9.3


\
 
 \ /
  Last update: 2012-03-13 01:27    [W:1.508 / U:0.740 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site