SUNRPC: Fix null-ptr-deref when xps sysfs alloc failed

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Fix null-ptr-deref when xps sysfs alloc failed There is a null-ptr-deref when xps sysfs alloc failed: BUG: KASAN: null-ptr-deref in sysfs_do_create_link_sd+0x40/0xd0 Read of size 8 at addr 0000000000000030 by task gssproxy/457 CPU: 5 PID: 457 Comm: gssproxy Not tainted 6.0.0-09040-g02357b27ee03 #9 Call Trace: <TASK> dump_stack_lvl+0x34/0x44 kasan_report+0xa3/0x120 sysfs_do_create_link_sd+0x40/0xd0 rpc_sysfs_client_setup+0x161/0x1b0 rpc_new_client+0x3fc/0x6e0 rpc_create_xprt+0x71/0x220 rpc_create+0x1d4/0x350 gssp_rpc_create+0xc3/0x160 set_gssp_clnt+0xbc/0x140 write_gssp+0x116/0x1a0 proc_reg_write+0xd6/0x130 vfs_write+0x177/0x690 ksys_write+0xb9/0x150 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 When the xprt_switch sysfs alloc failed, should not add xprt and switch sysfs to it, otherwise, maybe null-ptr-deref; also initialize the 'xps_sysfs' to NULL to avoid oops when destroy it.

References

• https://git.kernel.org/stable/c/d59722d088a9d86ce6d9d39979e5d1d669d249f7
• https://git.kernel.org/stable/c/7b189b0aa8dab14b49c31c65af8a982e96e25b62
• https://git.kernel.org/stable/c/cbdeaee94a415800c65a8c3fa04d9664a8b8fb3a