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Old 07-30-2012, 07:30 PM
Steve Conklin
 
Default udf: Fortify loading of sparing table

From: Jan Kara <jack@suse.cz>

CVE-2012-3400

BugLink: http://bugs.launchpad.net/bugs/1024497

Backported with changes to error prints from upstream commit 1df2ae31c724e57be9d7ac00d78db8a5dabdd050

Add sanity checks when loading sparing table from disk to avoid accessing
unallocated memory or writing to it.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Steve Conklin <sconklin@canonical.com>
---
fs/udf/super.c | 86 ++++++++++++++++++++++++++++++++++----------------------
1 file changed, 53 insertions(+), 33 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 7b27b06..4ea5ad8 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -56,6 +56,7 @@
#include <linux/seq_file.h>
#include <linux/bitmap.h>
#include <linux/crc-itu-t.h>
+#include <linux/log2.h>
#include <asm/byteorder.h>

#include "udf_sb.h"
@@ -1244,11 +1245,59 @@ out_bh:
return ret;
}

+static int udf_load_sparable_map(struct super_block *sb,
+ struct udf_part_map *map,
+ struct sparablePartitionMap *spm)
+{
+ uint32_t loc;
+ uint16_t ident;
+ struct sparingTable *st;
+ struct udf_sparing_data *sdata = &map->s_type_specific.s_sparing;
+ int i;
+ struct buffer_head *bh;
+
+ map->s_partition_type = UDF_SPARABLE_MAP15;
+ sdata->s_packet_len = le16_to_cpu(spm->packetLength);
+ if (!is_power_of_2(sdata->s_packet_len)) {
+ udf_error(sb, __func__,
+ "error loading logical volume descriptor: Invalid packet length %u
",
+ (unsigned)sdata->s_packet_len);
+ return -EIO;
+ }
+ if (spm->numSparingTables > 4) {
+ udf_error(sb, __func__,
+ "error loading logical volume descriptor: Too many sparing tables (%d)
",
+ (int)spm->numSparingTables);
+ return -EIO;
+ }
+
+ for (i = 0; i < spm->numSparingTables; i++) {
+ loc = le32_to_cpu(spm->locSparingTable[i]);
+ bh = udf_read_tagged(sb, loc, loc, &ident);
+ if (!bh)
+ continue;
+
+ st = (struct sparingTable *)bh->b_data;
+ if (ident != 0 ||
+ strncmp(st->sparingIdent.ident, UDF_ID_SPARING,
+ strlen(UDF_ID_SPARING)) ||
+ sizeof(*st) + le16_to_cpu(st->reallocationTableLen) >
+ sb->s_blocksize) {
+ brelse(bh);
+ continue;
+ }
+
+ sdata->s_spar_map[i] = bh;
+ }
+ map->s_partition_func = udf_get_pblock_spar15;
+ return 0;
+}
+
static int udf_load_logicalvol(struct super_block *sb, sector_t block,
struct kernel_lb_addr *fileset)
{
struct logicalVolDesc *lvd;
- int i, j, offset;
+ int i, offset;
uint8_t type;
struct udf_sb_info *sbi = UDF_SB(sb);
struct genericPartitionMap *gpm;
@@ -1304,38 +1353,9 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
} else if (!strncmp(upm2->partIdent.ident,
UDF_ID_SPARABLE,
strlen(UDF_ID_SPARABLE))) {
- uint32_t loc;
- struct sparingTable *st;
- struct sparablePartitionMap *spm =
- (struct sparablePartitionMap *)gpm;
-
- map->s_partition_type = UDF_SPARABLE_MAP15;
- map->s_type_specific.s_sparing.s_packet_len =
- le16_to_cpu(spm->packetLength);
- for (j = 0; j < spm->numSparingTables; j++) {
- struct buffer_head *bh2;
-
- loc = le32_to_cpu(
- spm->locSparingTable[j]);
- bh2 = udf_read_tagged(sb, loc, loc,
- &ident);
- map->s_type_specific.s_sparing.
- s_spar_map[j] = bh2;
-
- if (bh2 == NULL)
- continue;
-
- st = (struct sparingTable *)bh2->b_data;
- if (ident != 0 || strncmp(
- st->sparingIdent.ident,
- UDF_ID_SPARING,
- strlen(UDF_ID_SPARING))) {
- brelse(bh2);
- map->s_type_specific.s_sparing.
- s_spar_map[j] = NULL;
- }
- }
- map->s_partition_func = udf_get_pblock_spar15;
+ if (udf_load_sparable_map(sb, map,
+ (struct sparablePartitionMap *)gpm) < 0)
+ goto out_bh;
} else if (!strncmp(upm2->partIdent.ident,
UDF_ID_METADATA,
strlen(UDF_ID_METADATA))) {
--
1.7.9.5


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Old 07-30-2012, 07:47 PM
Andy Whitcroft
 
Default udf: Fortify loading of sparing table

On Mon, Jul 30, 2012 at 02:30:06PM -0500, Steve Conklin wrote:
> From: Jan Kara <jack@suse.cz>
>
> CVE-2012-3400
>
> BugLink: http://bugs.launchpad.net/bugs/1024497
>
> Backported with changes to error prints from upstream commit 1df2ae31c724e57be9d7ac00d78db8a5dabdd050

I suspect the above formatting will avoid the cve-autotraiger, i would
suggest:

[sconklin@canonical.com: port to old error prints]
backported from commit XXXX upstream

-apw

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