sysfs: check visibility before changing group attribute ownership

In the Linux kernel, the following vulnerability has been resolved: sysfs: check visibility before changing group attribute ownership Since commit 0c17270f9b92 ("net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)"), __dev_change_net_namespace() can hit WARN_ON() when trying to change owner of a file that isn't visible. See the trace below: WARNING: CPU: 6 PID: 2938 at net/core/dev.c:12410 __dev_change_net_namespace+0xb89/0xc30 CPU: 6 UID: 0 PID: 2938 Comm: incusd Not tainted 6.17.1-1-mainline #1 PREEMPT(full) 4b783b4a638669fb644857f484487d17cb45ed1f Hardware name: Framework Laptop 13 (AMD Ryzen 7040Series)/FRANMDCP07, BIOS 03.07 02/19/2025 RIP: 0010:__dev_change_net_namespace+0xb89/0xc30 [...] Call Trace: <TASK> ? if6_seq_show+0x30/0x50 do_setlink.isra.0+0xc7/0x1270 ? __nla_validate_parse+0x5c/0xcc0 ? security_capable+0x94/0x1a0 rtnl_newlink+0x858/0xc20 ? update_curr+0x8e/0x1c0 ? update_entity_lag+0x71/0x80 ? sched_balance_newidle+0x358/0x450 ? psi_task_switch+0x113/0x2a0 ? __pfx_rtnl_newlink+0x10/0x10 rtnetlink_rcv_msg+0x346/0x3e0 ? sched_clock+0x10/0x30 ? __pfx_rtnetlink_rcv_msg+0x10/0x10 netlink_rcv_skb+0x59/0x110 netlink_unicast+0x285/0x3c0 ? __alloc_skb+0xdb/0x1a0 netlink_sendmsg+0x20d/0x430 ____sys_sendmsg+0x39f/0x3d0 ? import_iovec+0x2f/0x40 ___sys_sendmsg+0x99/0xe0 __sys_sendmsg+0x8a/0xf0 do_syscall_64+0x81/0x970 ? __sys_bind+0xe3/0x110 ? syscall_exit_work+0x143/0x1b0 ? do_syscall_64+0x244/0x970 ? sock_alloc_file+0x63/0xc0 ? syscall_exit_work+0x143/0x1b0 ? do_syscall_64+0x244/0x970 ? alloc_fd+0x12e/0x190 ? put_unused_fd+0x2a/0x70 ? do_sys_openat2+0xa2/0xe0 ? syscall_exit_work+0x143/0x1b0 ? do_syscall_64+0x244/0x970 ? exc_page_fault+0x7e/0x1a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e [...] </TASK> Fix this by checking is_visible() before trying to touch the attribute.

Where it's fixed