File 0021-fs-squashfs-Use-kcalloc-when-releva.patch of Package u-boot.37698

From bf10be21f5bd112cc1a98a956d541c4b87f3477c Mon Sep 17 00:00:00 2001
From: Miquel Raynal <miquel.raynal@bootlin.com>
Date: Mon, 27 Jun 2022 12:20:03 +0200
Subject: [PATCH] fs/squashfs: Use kcalloc when relevant

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>
(cherry picked from commit 7f7fb9937c6cb49dd35153bd6708872b390b0a44)
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
 fs/squashfs/sqfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/squashfs/sqfs.c b/fs/squashfs/sqfs.c
index 92ab8ac631..ef4b5836b2 100644
--- a/fs/squashfs/sqfs.c
+++ b/fs/squashfs/sqfs.c
@@ -13,6 +13,7 @@
 #include <linux/types.h>
 #include <linux/byteorder/little_endian.h>
 #include <linux/byteorder/generic.h>
+#include <linux/compat.h>
 #include <memalign.h>
 #include <stdlib.h>
 #include <string.h>
@@ -725,7 +726,8 @@ static int sqfs_read_inode_table(unsigned char **inode_table)
 		goto free_itb;
 	}
 
-	*inode_table = malloc(metablks_count * SQFS_METADATA_BLOCK_SIZE);
+	*inode_table = kcalloc(metablks_count, SQFS_METADATA_BLOCK_SIZE,
+			       GFP_KERNEL);
 	if (!*inode_table) {
 		ret = -ENOMEM;
 		goto free_itb;