Re: [PATCH 1/1] RDMA/core: Fix "KASAN: slab-use-after-free Read in ib_register_device" problem

[Leon Romanovsky <leon@kernel.org>]

On Thu, May 01, 2025 at 12:36:02PM +0200, Zhu Yanjun wrote:
> 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
> 1d6a9e7449e2 ("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: 779e0bf47632 ("RDMA/core: Do not indicate device ready when device enablement fails")
> Reported-by: syzbot+e2ce9e275ecc70a30b72@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=e2ce9e275ecc70a30b72
> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> ---
>  drivers/infiniband/core/device.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> index b4e3e4beb7f4..59d84829dd66 100644
> --- a/drivers/infiniband/core/device.c
> +++ b/drivers/infiniband/core/device.c
> @@ -1468,8 +1468,12 @@ int ib_register_device(struct ib_device *device, const char *name,
>  		return ret;
>  	}
>  	dev_set_uevent_suppress(&device->dev, false);
> +
> +	/* device->dev.kobj->name should be protected by devices_rwsem */
> +	down_read(&devices_rwsem);
>  	/* Mark for userspace that device is ready */
>  	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
> +	up_read(&devices_rwsem);
>  
>  	ib_device_notify_register(device);

The change looks right to me, but I would ask you to put
kobject_uevent() into ib_device_notify_register() instead of adding
rwsem. It will ensure that both uevent and netlink will get same name.

Thanks

>  	ib_device_put(device);
> -- 
> 2.34.1
> 
>