ocfs2: fix uninitialized value in ocfs2_file_read_iter()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix uninitialized value in ocfs2_file_read_iter() Syzbot has reported the following KMSAN splat: BUG: KMSAN: uninit-value in ocfs2_file_read_iter+0x9a4/0xf80 ocfs2_file_read_iter+0x9a4/0xf80 __io_read+0x8d4/0x20f0 io_read+0x3e/0xf0 io_issue_sqe+0x42b/0x22c0 io_wq_submit_work+0xaf9/0xdc0 io_worker_handle_work+0xd13/0x2110 io_wq_worker+0x447/0x1410 ret_from_fork+0x6f/0x90 ret_from_fork_asm+0x1a/0x30 Uninit was created at: __alloc_pages_noprof+0x9a7/0xe00 alloc_pages_mpol_noprof+0x299/0x990 alloc_pages_noprof+0x1bf/0x1e0 allocate_slab+0x33a/0x1250 ___slab_alloc+0x12ef/0x35e0 kmem_cache_alloc_bulk_noprof+0x486/0x1330 __io_alloc_req_refill+0x84/0x560 io_submit_sqes+0x172f/0x2f30 __se_sys_io_uring_enter+0x406/0x41c0 __x64_sys_io_uring_enter+0x11f/0x1a0 x64_sys_call+0x2b54/0x3ba0 do_syscall_64+0xcd/0x1e0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Since an instance of 'struct kiocb' may be passed from the block layer with 'private' field uninitialized, introduce 'ocfs2_iocb_init_rw_locked()' and use it from where 'ocfs2_dio_end_io()' might take care, i.e. in 'ocfs2_file_read_iter()' and 'ocfs2_file_write_iter()'.

References

• https://git.kernel.org/stable/c/6c8f8d1e595dabd5389817f6d798cc8bd95c40ab
• https://git.kernel.org/stable/c/f4078ef38d3163e6be47403a619558b19c4bfccd
• https://git.kernel.org/stable/c/66b7ddd1804e2c4216dd7ead8eeb746cdbb3b62f
• https://git.kernel.org/stable/c/8c966150d5abff58c3c2bdb9a6e63fd773782905
• https://git.kernel.org/stable/c/83f8713a0ef1d55d6a287bcfadcaab8245ac5098
• https://git.kernel.org/stable/c/8e0de82ed18ba0e71f817adbd81317fd1032ca5a
• https://git.kernel.org/stable/c/366c933c2ab34dd6551acc03b4872726b7605143
• https://git.kernel.org/stable/c/dc78efe556fed162d48736ef24066f42e463e27c
• https://git.kernel.org/stable/c/adc77b19f62d7e80f98400b2fca9d700d2afdd6f