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