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. drivers/infiniband/core/device.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c index a666847bd714..1f0aabeabc4e 100644 --- a/drivers/infiniband/core/device.c +++ b/drivers/infiniband/core/device.c @@ -2016,6 +2016,7 @@ static int iw_query_port(struct ib_device *device, { struct in_device *inetdev; struct net_device *netdev; + int ret; memset(port_attr, 0, sizeof(*port_attr)); @@ -2045,8 +2046,13 @@ static int iw_query_port(struct ib_device *device, rcu_read_unlock(); } + /* + * netdev need to be put after query port since it might be dereferenced + * in some drivers such as siw. + */ + ret = device->ops.query_port(device, port_num, port_attr); dev_put(netdev); - return device->ops.query_port(device, port_num, port_attr); + return ret; } static int __ib_query_port(struct ib_device *device, -- 2.35.3
