RDMA/core: Fix "KASAN: slab-use-after-free Read in ib_register_device" problem

Call Trace:

 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 strlen+0x93/0xa0 lib/string.c:420
 __fortify_strlen include/linux/fortify-string.h:268 [inline]
 get_kobj_path_length lib/kobject.c:118 [inline]
 kobject_get_path+0x3f/0x2a0 lib/kobject.c:158
 kobject_uevent_env+0x289/0x1870 lib/kobject_uevent.c:545
 ib_register_device drivers/infiniband/core/device.c:1472 [inline]
 ib_register_device+0x8cf/0xe00 drivers/infiniband/core/device.c:1393
 rxe_register_device+0x275/0x320 drivers/infiniband/sw/rxe/rxe_verbs.c:1552
 rxe_net_add+0x8e/0xe0 drivers/infiniband/sw/rxe/rxe_net.c:550
 rxe_newlink+0x70/0x190 drivers/infiniband/sw/rxe/rxe.c:225
 nldev_newlink+0x3a3/0x680 drivers/infiniband/core/nldev.c:1796
 rdma_nl_rcv_msg+0x387/0x6e0 drivers/infiniband/core/netlink.c:195
 rdma_nl_rcv_skb.constprop.0.isra.0+0x2e5/0x450
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
 __sys_sendmsg+0x16d/0x220 net/socket.c:2652
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

This problem is similar to the problem that the
commit 1d6a9e7 ("RDMA/core: Fix use-after-free when rename device name")
fixes.

The root cause is: the function ib_device_rename() renames the name with
lock. But in the function kobject_uevent(), this name is accessed without
lock protection at the same time.

The solution is to add the lock protection when this name is accessed in
the function kobject_uevent().

Fixes: 779e0bf ("RDMA/core: Do not indicate device ready when device enablement fails")
Link: https://patch.msgid.link/r/20250506151008.75701-1-yanjun.zhu@linux.dev
Reported-by: syzbot+e2ce9e275ecc70a30b72@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=e2ce9e275ecc70a30b72
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: zhuyj

drivers/infiniband/core/device.c

@@ -1352,6 +1352,9 @@ static void ib_device_notify_register(struct ib_device *device)
 
 	down_read(&devices_rwsem);
 
+	/* Mark for userspace that device is ready */
+	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
+
 	ret = rdma_nl_notify_event(device, 0, RDMA_REGISTER_EVENT);
 	if (ret)
 		goto out;
@@ -1468,10 +1471,9 @@ int ib_register_device(struct ib_device *device, const char *name,
 		return ret;
 	}
 	dev_set_uevent_suppress(&device->dev, false);
-	/* Mark for userspace that device is ready */
-	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
 
 	ib_device_notify_register(device);
+
 	ib_device_put(device);
 
 	return 0;