[PATCH] drivers/misc/vmw_vmci: restrict too big queue size in qp_host_alloc_queue

From: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
To: arnd@arndb.de, gregkh@linuxfoundation.org
Cc: alex.dewar90@gmail.com, linux-kernel@vger.kernel.org,
	syzbot+15ec7391f3d6a1a7cc7d@syzkaller.appspotmail.com
Subject: [PATCH] drivers/misc/vmw_vmci: restrict too big queue size in qp_host_alloc_queue
Date: Sat,  6 Feb 2021 11:34:09 +0600	[thread overview]
Message-ID: <20210206053409.1972270-1-snovitoll@gmail.com> (raw)

syzbot found WARNING in qp_broker_alloc[1] in qp_host_alloc_queue()
when num_pages is 0x100001, giving queue_size + queue_page_size
bigger than KMALLOC_MAX_SIZE for kzalloc(), resulting order >= MAX_ORDER
condition.

queue_size + queue_page_size=0x8000d8, where KMALLOC_MAX_SIZE=0x400000.


FYI, I've also noticed in vmci_queue_pair.c other SLAB allocations with no
length check that might exceed KMALLOC_MAX_SIZE as well,
but syzbot doesn't have reproduces for them.

in qp_alloc_ppn_set():
	produce_ppns =
	    kmalloc_array(num_produce_pages, sizeof(*produce_ppns),
			  GFP_KERNEL);
[..]
	consume_ppns =
	    kmalloc_array(num_consume_pages, sizeof(*consume_ppns),
			  GFP_KERNEL);
[..]
in qp_alloc_hypercall():
	msg_size = sizeof(*alloc_msg) +
	    (size_t) entry->num_ppns * ppn_size;
	alloc_msg = kmalloc(msg_size, GFP_KERNEL);
[..]
in qp_broker_create():
	entry->local_mem = kcalloc(QPE_NUM_PAGES(entry->qp),
					   PAGE_SIZE, GFP_KERNEL);

[1]
Call Trace:
 alloc_pages include/linux/gfp.h:547 [inline]
 kmalloc_order+0x40/0x130 mm/slab_common.c:837
 kmalloc_order_trace+0x15/0x70 mm/slab_common.c:853
 kmalloc_large include/linux/slab.h:481 [inline]
 __kmalloc+0x257/0x330 mm/slub.c:3959
 kmalloc include/linux/slab.h:557 [inline]
 kzalloc include/linux/slab.h:682 [inline]
 qp_host_alloc_queue drivers/misc/vmw_vmci/vmci_queue_pair.c:540 [inline]
 qp_broker_create drivers/misc/vmw_vmci/vmci_queue_pair.c:1351 [inline]
 qp_broker_alloc+0x936/0x2740 drivers/misc/vmw_vmci/vmci_queue_pair.c:1739

Reported-by: syzbot+15ec7391f3d6a1a7cc7d@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
---
 drivers/misc/vmw_vmci/vmci_queue_pair.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c
index c49065887e8f..f6af406fda80 100644
--- a/drivers/misc/vmw_vmci/vmci_queue_pair.c
+++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c
@@ -537,6 +537,11 @@ static struct vmci_queue *qp_host_alloc_queue(u64 size)
 
 	queue_page_size = num_pages * sizeof(*queue->kernel_if->u.h.page);
 
+	if (queue_size + queue_page_size > KMALLOC_MAX_SIZE) {
+		pr_warn("too big queue to allocate\n");
+		return NULL;
+	}
+
 	queue = kzalloc(queue_size + queue_page_size, GFP_KERNEL);
 	if (queue) {
 		queue->q_header = NULL;
-- 
2.25.1

