A crafted squashfs image could embed a huge number of empty metadata
blocks in order to make the amount of malloc()'d memory overflow and be
much smaller than expected. Because of this flaw, any random code
positioned at the right location in the squashfs image could be memcpy'd
from the squashfs structures into U-Boot code location while trying to
access the rearmost blocks, before being executed.

In order to prevent this vulnerability from being exploited in eg. a
secure boot environment, let's add a check over the amount of data
that is going to be allocated. Such a check could look like:

if (!elem_size || n > SIZE_MAX / elem_size)
	return NULL;

The right way to do it would be to enhance the calloc() implementation
but this is quite an impacting change for such a small fix. Another
solution would be to add the check before the malloc call in the
squashfs implementation, but this does not look right. So for now, let's
use the kcalloc() compatibility function from Linux, which has this
check.

Fixes: c5100613037 ("fs/squashfs: new filesystem")
Reported-by: Tatsuhiko Yasumatsu <Tatsuhiko.Yasumatsu@sony.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Tatsuhiko Yasumatsu <Tatsuhiko.Yasumatsu@sony.com>

Following Jincheng's report, an out-of-band write leading to arbitrary
code execution is possible because on one side the squashfs logic
accepts directory names up to 65535 bytes (u16), while U-Boot fs logic
accepts directory names up to 255 bytes long.

Prevent such an exploit from happening by capping directory name sizes
to 255. Use a define for this purpose so that developers can link the
limitation to its source and eventually kill it some day by dynamically
allocating this array (if ever desired).

Link: https://lore.kernel.org/all/CALO=DHFB+yBoXxVr5KcsK0iFdg+e7ywko4-e+72kjbcS8JBfPw@mail.gmail.com
Reported-by: Jincheng Wang <jc.w4ng@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Jincheng Wang <jc.w4ng@gmail.com>

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>

Commit b1a14f8a1c2e ("UBIFS: Change ubifsload to not read beyond the
requested size") added optimization to do not read more bytes than it is
really needed. But this commit introduced incorrect handling of the hole at
the end of file. This logic cause U-Boot to crash or lockup when trying to
read from the ubifs filesystem.

When read_block() call returns -ENOENT error (not an error, but the hole)
then dn-> structure is not filled and contain garbage. So using of dn->size
for memcpy() argument cause that U-Boot tries to copy unspecified amount of
bytes from possible unmapped memory. Which randomly cause lockup of P2020
CPU.

Fix this issue by copying UBIFS_BLOCK_SIZE bytes from read buffer when
dn->size is not available. UBIFS_BLOCK_SIZE is the size of the buffer
itself and read_block() fills buffer by zeros when it returns -ENOENT.

This patch fixes ubifsload on P2020.

Fixes: b1a14f8a1c2e ("UBIFS: Change ubifsload to not read beyond the requested size")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>

When compling for x86:
ld.bfd: fs/squashfs/sqfs.o: in function `sqfs_read':
u-boot/fs/squashfs/sqfs.c:1443: undefined reference to `__udivmoddi4'
ld.bfd: u-boot/fs/squashfs/sqfs.c:1521: undefined reference to `__udivmoddi4'

Signed-off-by: Sean Nyekjaer <sean.nyekjaer.ext@siemensgamesa.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Pali Rohár <pali@kernel.org>

It is helpful to be able to try out bootstd on sandbox, using host files.
This is easier than using a block device, which must have a filesystem,
partition table, etc.

Add a new driver which provides this feature. For now it is not used in
tests, but it is likely to be useful.

Add notes in the devicetree also, but don't disturb the tests.

Signed-off-by: Simon Glass <sjg@chromium.org>

When sandbox is used with hostfs we won't have a block device, but still
must set up the filesystem type before any filesystem operation, such as
loading a file. Add a function to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>

Implementation in linux/crc16.h provides standard CRC-16 algorithm with
polynomial x^16 + x^15 + x^2 + 1. Use it and remove duplicate ext4 CRC-16
specific code.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>

This implementation provides standard CRC-16 algorithm with polynomial
x^16 + x^15 + x^2 + 1.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>

File fs/ubifs/crc16.h is standard linux's crc16.h include file. So move it
from fs/ubifs to include/linux where are also other linux include files.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>