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BUG: KMSAN: uninit-value in iov_iter_alignment_iovec+0x1a8/0x470 lib/iov_iter.c:894
 iov_iter_alignment_iovec+0x1a8/0x470 lib/iov_iter.c:894
 iov_iter_alignment+0x1ac/0x2d0 lib/iov_iter.c:939
 exfat_file_write_iter+0x1df/0xcb0 fs/exfat/file.c:594
 io_write+0xd41/0x2380 io_uring/rw.c:1122
 io_issue_sqe+0x436/0x1f60 io_uring/io_uring.c:1735
 io_queue_sqe io_uring/io_uring.c:1945 [inline]
 io_submit_sqe io_uring/io_uring.c:2200 [inline]
 io_submit_sqes+0x11bc/0x2f80 io_uring/io_uring.c:2317
 __do_sys_io_uring_enter io_uring/io_uring.c:3368 [inline]
 __se_sys_io_uring_enter+0x41d/0x4da0 io_uring/io_uring.c:3303
 __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3303
 x64_sys_call+0xce5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4125 [inline]
 slab_alloc_node mm/slub.c:4168 [inline]
 __do_kmalloc_node mm/slub.c:4297 [inline]
 __kmalloc_noprof+0x923/0x1230 mm/slub.c:4310
 kmalloc_noprof include/linux/slab.h:905 [inline]
 io_cache_alloc io_uring/alloc_cache.h:37 [inline]
 io_uring_alloc_async_data io_uring/io_uring.h:232 [inline]
 io_rw_alloc_async io_uring/rw.c:224 [inline]
 io_prep_rw_setup io_uring/rw.c:240 [inline]
 io_prep_rw+0x9f4/0x1300 io_uring/rw.c:319
 io_prep_rwv+0xb3/0x510 io_uring/rw.c:354
 io_prep_writev+0x3a/0x50 io_uring/rw.c:374
 io_init_req io_uring/io_uring.c:2115 [inline]
 io_submit_sqe io_uring/io_uring.c:2162 [inline]
 io_submit_sqes+0x1082/0x2f80 io_uring/io_uring.c:2317
 __do_sys_io_uring_enter io_uring/io_uring.c:3368 [inline]
 __se_sys_io_uring_enter+0x41d/0x4da0 io_uring/io_uring.c:3303
 __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3303
 x64_sys_call+0xce5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 15821 Comm: syz.7.2960 Not tainted 6.13.0-syzkaller-00918-g95ec54a420b8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
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