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authorPhillip Lougher <phillip@lougher.demon.co.uk>2011-05-24 04:15:21 +0100
committerPhillip Lougher <phillip@lougher.demon.co.uk>2011-05-25 18:21:32 +0100
commitac51a0a7139aa93bf1176b701c86fa3d2bdf6106 (patch)
tree776d75b5cd1712d43feecc698b855173ed6ee57f /fs/squashfs/export.c
parent37986f63c81bf23c856f65fc5e4830550e7f3d5b (diff)
downloadlinux-linaro-stable-ac51a0a7139aa93bf1176b701c86fa3d2bdf6106.tar.gz
Squashfs: add sanity checks to lookup table reading at mount time
Fsfuzzer generates corrupted filesystems which throw a warn_on in kmalloc. One of these is due to a corrupted superblock inodes field. Fix this by checking that the number of bytes to be read (and allocated) does not extend into the next filesystem structure. Also add a couple of other sanity checks of the mount-time lookup table structures. Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
Diffstat (limited to 'fs/squashfs/export.c')
-rw-r--r--fs/squashfs/export.c29
1 files changed, 27 insertions, 2 deletions
diff --git a/fs/squashfs/export.c b/fs/squashfs/export.c
index cc6dd90cee6a..e3108711a40a 100644
--- a/fs/squashfs/export.c
+++ b/fs/squashfs/export.c
@@ -121,13 +121,38 @@ static struct dentry *squashfs_get_parent(struct dentry *child)
* Read uncompressed inode lookup table indexes off disk into memory
*/
__le64 *squashfs_read_inode_lookup_table(struct super_block *sb,
- u64 lookup_table_start, unsigned int inodes)
+ u64 lookup_table_start, u64 next_table, unsigned int inodes)
{
unsigned int length = SQUASHFS_LOOKUP_BLOCK_BYTES(inodes);
+ __le64 *table;
TRACE("In read_inode_lookup_table, length %d\n", length);
- return squashfs_read_table(sb, lookup_table_start, length);
+ /* Sanity check values */
+
+ /* there should always be at least one inode */
+ if (inodes == 0)
+ return ERR_PTR(-EINVAL);
+
+ /* length bytes should not extend into the next table - this check
+ * also traps instances where lookup_table_start is incorrectly larger
+ * than the next table start
+ */
+ if (lookup_table_start + length > next_table)
+ return ERR_PTR(-EINVAL);
+
+ table = squashfs_read_table(sb, lookup_table_start, length);
+
+ /*
+ * table[0] points to the first inode lookup table metadata block,
+ * this should be less than lookup_table_start
+ */
+ if (!IS_ERR(table) && table[0] >= lookup_table_start) {
+ kfree(table);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return table;
}