[PATCH 4.9 18/53] squashfs: fix inode lookup sanity checks

Greg Kroah-Hartman
2021-03-29T08:03:30Z

From: Sean Nyekjaer <sean@geanix.com>

commit c1b2028315c6b15e8d6725e0d5884b15887d3daa upstream.

When mouting a squashfs image created without inode compression it fails
with: "unable to read inode lookup table"

It turns out that the BLOCK_OFFSET is missing when checking the
SQUASHFS_METADATA_SIZE agaist the actual size.

Link: https://lkml.kernel.org/r/20210226092903.1473545-1-sean@geanix.com
Fixes: eabac19e40c0 ("squashfs: add more sanity checks in inode lookup")
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Acked-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/squashfs/export.c | 8 ++++++--
fs/squashfs/squashfs_fs.h | 1 +
2 files changed, 7 insertions(+), 2 deletions(-)

--- a/fs/squashfs/export.c
+++ b/fs/squashfs/export.c
@@ -165,14 +165,18 @@ __le64 *squashfs_read_inode_lookup_table
start = le64_to_cpu(table[n]);
end = le64_to_cpu(table[n + 1]);

- if (start >= end || (end - start) > SQUASHFS_METADATA_SIZE) {
+ if (start >= end
+ || (end - start) >
+ (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
kfree(table);
return ERR_PTR(-EINVAL);
}
}

start = le64_to_cpu(table[indexes - 1]);
- if (start >= lookup_table_start || (lookup_table_start - start) > SQUASHFS_METADATA_SIZE) {
+ if (start >= lookup_table_start ||
+ (lookup_table_start - start) >
+ (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
kfree(table);
return ERR_PTR(-EINVAL);
}
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -30,6 +30,7 @@

/* size of metadata (inode and directory) blocks */
#define SQUASHFS_METADATA_SIZE 8192
+#define SQUASHFS_BLOCK_OFFSET 2

/* default size of block device I/O */
#ifdef CONFIG_SQUASHFS_4K_DEVBLK_SIZE