From 353748a359f1821ee934afc579cf04572406b420 Mon Sep 17 00:00:00 2001
From: Silvio Cesare <silvio.cesare@gmail.com>
Date: Fri, 4 May 2018 13:44:02 +1000
Subject: [PATCH] UBIFS: Fix potential integer overflow in allocation
Git-commit: 353748a359f1821ee934afc579cf04572406b420
Patch-mainline: v4.18-rc1
References: bsc#1051510

There is potential for the size and len fields in ubifs_data_node to be
too large causing either a negative value for the length fields or an
integer overflow leading to an incorrect memory allocation. Likewise,
when the len field is small, an integer underflow may occur.

Signed-off-by: Silvio Cesare <silvio.cesare@gmail.com>
Fixes: 1e51764a3c2ac ("UBIFS: add new flash file system")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 fs/ubifs/journal.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index da8afdfccaa6..07b4956e0425 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -1282,10 +1282,11 @@ static int truncate_data_node(const struct ubifs_info *c, const struct inode *in
 			      int *new_len)
 {
 	void *buf;
-	int err, dlen, compr_type, out_len, old_dlen;
+	int err, compr_type;
+	u32 dlen, out_len, old_dlen;
 
 	out_len = le32_to_cpu(dn->size);
-	buf = kmalloc(out_len * WORST_COMPR_FACTOR, GFP_NOFS);
+	buf = kmalloc_array(out_len, WORST_COMPR_FACTOR, GFP_NOFS);
 	if (!buf)
 		return -ENOMEM;
 
-- 
2.18.0