linux-kernel - [PATCH 3.18 064/185] kernel/relay.c: limit kmalloc size to KMALLOC_MAX

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Date:   Mon, 28 May 2018 12:01:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Rientjes <rientjes@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jens Axboe <axboe@...nel.dk>,
        Dave Jiang <dave.jiang@...el.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 3.18 064/185] kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE

3.18-stable review patch.  If anyone has any objections, please let me know.

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

From: David Rientjes <rientjes@...gle.com>

[ Upstream commit 88913bd8ea2a75d7e460a4bed5f75e1c32660d7e ]

chan->n_subbufs is set by the user and relay_create_buf() does a kmalloc()
of chan->n_subbufs * sizeof(size_t *).

kmalloc_slab() will generate a warning when this fails if
chan->subbufs * sizeof(size_t *) > KMALLOC_MAX_SIZE.

Limit chan->n_subbufs to the maximum allowed kmalloc() size.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802061216100.122576@chino.kir.corp.google.com
Fixes: f6302f1bcd75 ("relay: prevent integer overflow in relay_open()")
Signed-off-by: David Rientjes <rientjes@...gle.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Dave Jiang <dave.jiang@...el.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 kernel/relay.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -166,7 +166,7 @@ static struct rchan_buf *relay_create_bu
 {
 	struct rchan_buf *buf;
 
-	if (chan->n_subbufs > UINT_MAX / sizeof(size_t *))
+	if (chan->n_subbufs > KMALLOC_MAX_SIZE / sizeof(size_t *))
 		return NULL;
 
 	buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);