RDMA/core: Fix use-after-free when rename device name

RDMA/core: Fix use-after-free when rename device name

Syzbot reported a slab-use-after-free with the following call trace:

==================================================================
BUG: KASAN: slab-use-after-free in nla_put+0xd3/0x150 lib/nlattr.c:1099
Read of size 5 at addr ffff888140ea1c60 by task syz.0.988/10025

CPU: 0 UID: 0 PID: 10025 Comm: syz.0.988
Not tainted 6.14.0-rc4-syzkaller-00859-gf77f12010f67 #0
Hardware name: Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 nla_put+0xd3/0x150 lib/nlattr.c:1099
 nla_put_string include/net/netlink.h:1621 [inline]
 fill_nldev_handle+0x16e/0x200 drivers/infiniband/core/nldev.c:265
 rdma_nl_notify_event+0x561/0xef0 drivers/infiniband/core/nldev.c:2857
 ib_device_notify_register+0x22/0x230 drivers/infiniband/core/device.c:1344
 ib_register_device+0x1292/0x1460 drivers/infiniband/core/device.c:1460
 rxe_register_device+0x233/0x350 drivers/infiniband/sw/rxe/rxe_verbs.c:1540
 rxe_net_add+0x74/0xf0 drivers/infiniband/sw/rxe/rxe_net.c:550
 rxe_newlink+0xde/0x1a0 drivers/infiniband/sw/rxe/rxe.c:212
 nldev_newlink+0x5ea/0x680 drivers/infiniband/core/nldev.c:1795
 rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
 rdma_nl_rcv+0x6dd/0x9e0 drivers/infiniband/core/netlink.c:259
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:724
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2564
 ___sys_sendmsg net/socket.c:2618 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2650
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f42d1b8d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 ...
RSP: 002b:00007f42d2960038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f42d1da6320 RCX: 00007f42d1b8d169
RDX: 0000000000000000 RSI: 00004000000002c0 RDI: 000000000000000c
RBP: 00007f42d1c0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f42d1da6320 R15: 00007ffe399344a8
 </TASK>

Allocated by task 10025:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4294 [inline]
 __kmalloc_node_track_caller_noprof+0x28b/0x4c0 mm/slub.c:4313
 __kmemdup_nul mm/util.c:61 [inline]
 kstrdup+0x42/0x100 mm/util.c:81
 kobject_set_name_vargs+0x61/0x120 lib/kobject.c:274
 dev_set_name+0xd5/0x120 drivers/base/core.c:3468
 assign_name drivers/infiniband/core/device.c:1202 [inline]
 ib_register_device+0x178/0x1460 drivers/infiniband/core/device.c:1384
 rxe_register_device+0x233/0x350 drivers/infiniband/sw/rxe/rxe_verbs.c:1540
 rxe_net_add+0x74/0xf0 drivers/infiniband/sw/rxe/rxe_net.c:550
 rxe_newlink+0xde/0x1a0 drivers/infiniband/sw/rxe/rxe.c:212
 nldev_newlink+0x5ea/0x680 drivers/infiniband/core/nldev.c:1795
 rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
 rdma_nl_rcv+0x6dd/0x9e0 drivers/infiniband/core/netlink.c:259
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:724
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2564
 ___sys_sendmsg net/socket.c:2618 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2650
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 10035:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2353 [inline]
 slab_free mm/slub.c:4609 [inline]
 kfree+0x196/0x430 mm/slub.c:4757
 kobject_rename+0x38f/0x410 lib/kobject.c:524
 device_rename+0x16a/0x200 drivers/base/core.c:4525
 ib_device_rename+0x270/0x710 drivers/infiniband/core/device.c:402
 nldev_set_doit+0x30e/0x4c0 drivers/infiniband/core/nldev.c:1146
 rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
 rdma_nl_rcv+0x6dd/0x9e0 drivers/infiniband/core/netlink.c:259
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:724
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2564
 ___sys_sendmsg net/socket.c:2618 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2650
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

This is because if rename device happens, the old name is freed in
ib_device_rename() with lock, but ib_device_notify_register() may visit
the dev name locklessly by event RDMA_REGISTER_EVENT or
RDMA_NETDEV_ATTACH_EVENT.

Fix this by hold devices_rwsem in ib_device_notify_register().

Reported-by: syzbot+f60349ba1f9f08df349f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=25bc6f0ed2b88b9eb9b8
Fixes: 9cbed5aab5ae ("RDMA/nldev: Add support for RDMA monitoring")
Signed-off-by: Wang Liang <wangliang74@huawei.com>
Link: https://patch.msgid.link/20250313092421.944658-1-wangliang74@huawei.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>