Squashfs: add sanity checks to id reading at mount time
Fsfuzzer generates corrupted filesystems which throw a warn_on in
kmalloc. One of these is due to a corrupted superblock no_ids 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 id table
structures.
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 401cc8c..8f5f278 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -83,7 +83,7 @@
long long root_inode;
unsigned short flags;
unsigned int fragments;
- u64 lookup_table_start, xattr_id_table_start;
+ u64 lookup_table_start, xattr_id_table_start, next_table;
int err;
TRACE("Entered squashfs_fill_superblock\n");
@@ -217,8 +217,10 @@
/* Handle xattrs */
sb->s_xattr = squashfs_xattr_handlers;
xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
- if (xattr_id_table_start == SQUASHFS_INVALID_BLK)
+ if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
+ next_table = msblk->bytes_used;
goto allocate_id_index_table;
+ }
/* Allocate and read xattr id lookup table */
msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
@@ -230,11 +232,13 @@
if (err != -ENOTSUPP)
goto failed_mount;
}
+ next_table = msblk->xattr_table;
allocate_id_index_table:
/* Allocate and read id index table */
msblk->id_table = squashfs_read_id_index_table(sb,
- le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids));
+ le64_to_cpu(sblk->id_table_start), next_table,
+ le16_to_cpu(sblk->no_ids));
if (IS_ERR(msblk->id_table)) {
ERROR("unable to read id index table\n");
err = PTR_ERR(msblk->id_table);