File 0041-fs-squashfs-Use-kcalloc-when-releva.patch of Package u-boot.25329

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File 0041-fs-squashfs-Use-kcalloc-when-releva.patch of Package u-boot.25329

From ef740fe3e805d50220289a38336cb2c25a58ec68 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 5de69ac3ca..e6e8b06061 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;

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File 0041-fs-squashfs-Use-kcalloc-when-releva.patch of Package u-boot.25329

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