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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Silvio Cesare" <silvio.cesare@gmail.com>,
        "Kees Cook" <keescook@chromium.org>
Date:   Sun, 11 Nov 2018 19:49:05 +0000
Message-ID: <lsq.1541965745.578061426@decadent.org.uk>
Subject: [PATCH 3.16 134/366] UBIFS: Fix potential integer overflow in
 allocation
In-Reply-To: <lsq.1541965744.387173642@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Silvio Cesare <silvio.cesare@gmail.com>

commit 353748a359f1821ee934afc579cf04572406b420 upstream.

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")
Signed-off-by: Kees Cook <keescook@chromium.org>
[bwh: Backported to 3.16: We have a different set of length variables in
 recomp_data_node()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/ubifs/journal.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -1099,10 +1099,11 @@ out_free:
 static int recomp_data_node(struct ubifs_data_node *dn, int *new_len)
 {
 	void *buf;
-	int err, len, compr_type, out_len;
+	int err, compr_type;
+	u32 len, out_len;
 
 	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;