On 5/19/23 22:05, Chuck Lever III wrote:
On May 19, 2023, at 10:03 AM, Jason Gunthorpe <jgg@xxxxxxxx> wrote:
On Fri, May 19, 2023 at 11:11:19AM +0800, Guoqing Jiang wrote:
There is a UAF report by syzbot.
BUG: KASAN: slab-use-after-free in siw_query_port+0x37b/0x3e0 drivers/infiniband/sw/siw/siw_verbs.c:177
Read of size 4 at addr ffff888034efa0e8 by task kworker/1:4/24211
CPU: 1 PID: 24211 Comm: kworker/1:4 Not tainted 6.4.0-rc1-syzkaller-00012-g16a8829130ca #0
Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Workqueue: infiniband ib_cache_event_task
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351
print_report mm/kasan/report.c:462 [inline]
kasan_report+0x11c/0x130 mm/kasan/report.c:572
siw_query_port+0x37b/0x3e0 drivers/infiniband/sw/siw/siw_verbs.c:177
iw_query_port drivers/infiniband/core/device.c:2049 [inline]
ib_query_port drivers/infiniband/core/device.c:2090 [inline]
ib_query_port+0x3c4/0x8f0 drivers/infiniband/core/device.c:2082
ib_cache_update.part.0+0xcf/0x920 drivers/infiniband/core/cache.c:1487
ib_cache_update drivers/infiniband/core/cache.c:1561 [inline]
ib_cache_event_task+0x1b1/0x270 drivers/infiniband/core/cache.c:1561
process_one_work+0x99a/0x15e0 kernel/workqueue.c:2405
worker_thread+0x67d/0x10c0 kernel/workqueue.c:2552
kthread+0x344/0x440 kernel/kthread.c:379
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
It happened because netdev could be freed if the last reference
is released, but drivers still dereference netdev in query_port.
So let's guard query_port with dev_hold and dev_put.
Reported-by: syzbot+79f283f1f4ccc6e8b624@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/lkml/0000000000001f992805fb79ce97@xxxxxxxxxx/
Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxx>
---
I guess another option could be call ib_device_get_netdev to get
netdev in siw_query_port instead of dereference netdev directly.
If so, then other drivers (irdma_query_port and ocrdma_query_port)
may need to make relevant change as well.
Something is wrong in siw if it is UAF'ing it's own memory:
attr->max_mtu = ib_mtu_int_to_enum(sdev->netdev->mtu);
It needs to protect sedv->netdev somehow on its own.
Note that netdev is actually the underlying device. An siw device
doesn't have its own. But maybe it should.
I go through siw code a bit, and can't find relevant protection in siw.
Let me cc Bernard.
Thanks,
Guoqing
