io-wq: Fix memory leak in worker creation

In the Linux kernel, the following vulnerability has been resolved:

io-wq: Fix memory leak in worker creation

If the CPU mask allocation for a node fails, then the memory allocated for

the 'io_wqe' struct of the current node doesn't get freed on the error

handling path, since it has not yet been added to the 'wqes' array.

This was spotted when fuzzing v6.1-rc1 with Syzkaller:

BUG: memory leak

unreferenced object 0xffff8880093d5000 (size 1024):

comm "syz-executor.2", pid 7701, jiffies 4295048595 (age 13.900s)

hex dump (first 32 bytes):

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

backtrace:

[<00000000cb463369>] __kmem_cache_alloc_node+0x18e/0x720

[<00000000147a3f9c>] kmalloc_node_trace+0x2a/0x130

[<000000004e107011>] io_wq_create+0x7b9/0xdc0

[<00000000c38b2018>] io_uring_alloc_task_context+0x31e/0x59d

[<00000000867399da>] __io_uring_add_tctx_node.cold+0x19/0x1ba

[<000000007e0e7a79>] io_uring_setup.cold+0x1b80/0x1dce

[<00000000b545e9f6>] __x64_sys_io_uring_setup+0x5d/0x80

[<000000008a8a7508>] do_syscall_64+0x5d/0x90

[<000000004ac08bec>] entry_SYSCALL_64_after_hwframe+0x63/0xcd