linux-kernel - [PATCH] [38/98] Fix corrupted OSF partition table parsing

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Date:	Tue, 26 Jul 2011 17:35:30 -0700 (PDT)
From:	Andi Kleen <andi@...stfloor.org>
To:	Warns@...-sense.de, warns@...-sense.de, stable@...nel.org,
	ak@...ux.intel.com, torvalds@...ux-foundation.org, gregkh@...e.de,
	linux-kernel@...r.kernel.org, stable@...nel.org,
	tim.bird@...sony.com, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH] [38/98] Fix corrupted OSF partition table parsing

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Timo Warns <Warns@...-sense.de>

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@...-sense.de>
Cc: stable@...nel.org
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
[ 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@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 fs/partitions/osf.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Index: linux-2.6.35.y/fs/partitions/osf.c
===================================================================
--- linux-2.6.35.y.orig/fs/partitions/osf.c
+++ linux-2.6.35.y/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)
 {
 	int i;
 	int slot = 1;
+	unsigned int npartitions;
 	Sector sect;
 	unsigned char *data;
 	struct disklabel {
@@ -45,7 +48,7 @@ int osf_partition(struct parsed_partitio
 			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_partitio
 		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))
--
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