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Subject[34-longterm 127/196] Fix corrupted OSF partition table parsing
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 1eafbfeb7bdf59cfe173304c76188f3fd5f1fd05 upstream.

The kernel automatically evaluates partition tables of storage devices.
The code for evaluating OSF partitions contains a bug that leaks data
from kernel heap memory to userspace for certain corrupted OSF
partitions.

In more detail:

for (i = 0 ; i < le16_to_cpu(label->d_npartitions); i++, partition++) {
iterates from 0 to d_npartitions - 1, where d_npartitions is read from
the partition table without validation and partition is a pointer to an
array of at most 8 d_partitions.

Add the proper and obvious validation.

Signed-off-by: Timo Warns <warns@pre-sense.de>
[ Changed the patch trivially to not repeat the whole le16_to_cpu()
thing, and to use an explicit constant for the magic value '8' ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
fs/partitions/osf.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/partitions/osf.c b/fs/partitions/osf.c
index c05c17bc..6e0825e 100644
--- a/fs/partitions/osf.c
+++ b/fs/partitions/osf.c
@@ -10,10 +10,13 @@
#include "check.h"
#include "osf.h"

+#define MAX_OSF_PARTITIONS 8
+
int osf_partition(struct parsed_partitions *state, struct block_device *bdev)
{
int i;
int slot = 1;
+ unsigned int npartitions;
Sector sect;
unsigned char *data;
struct disklabel {
@@ -45,7 +48,7 @@ int osf_partition(struct parsed_partitions *state, struct block_device *bdev)
u8 p_fstype;
u8 p_frag;
__le16 p_cpg;
- } d_partitions[8];
+ } d_partitions[MAX_OSF_PARTITIONS];
} * label;
struct d_partition * partition;

@@ -63,7 +66,12 @@ int osf_partition(struct parsed_partitions *state, struct block_device *bdev)
put_dev_sector(sect);
return 0;
}
- for (i = 0 ; i < le16_to_cpu(label->d_npartitions); i++, partition++) {
+ npartitions = le16_to_cpu(label->d_npartitions);
+ if (npartitions > MAX_OSF_PARTITIONS) {
+ put_dev_sector(sect);
+ return 0;
+ }
+ for (i = 0 ; i < npartitions; i++, partition++) {
if (slot == state->limit)
break;
if (le32_to_cpu(partition->p_size))
--
1.7.9.3


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