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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+0x1f1/0x12a0 fs/exfat/file.c:588
 io_write+0xd5a/0x2360 io_uring/rw.c:1082
 io_issue_sqe+0x420/0x2130 io_uring/io_uring.c:1736
 io_wq_submit_work+0xaf9/0xdc0 io_uring/io_uring.c:1845
 io_worker_handle_work+0xd11/0x2110 io_uring/io-wq.c:601
 io_wq_worker+0x447/0x1410 io_uring/io-wq.c:655
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

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_alloc_async_data+0xc0/0x220 io_uring/io_uring.c:1647
 io_rw_alloc_async io_uring/rw.c:228 [inline]
 io_prep_rw_setup io_uring/rw.c:245 [inline]
 io_prep_rw+0x921/0xcd0 io_uring/rw.c:286
 io_prep_rwv+0xb3/0x510 io_uring/rw.c:305
 io_prep_writev+0x3a/0x50 io_uring/rw.c:325
 io_init_req io_uring/io_uring.c:2116 [inline]
 io_submit_sqe io_uring/io_uring.c:2163 [inline]
 io_submit_sqes+0x1082/0x2f80 io_uring/io_uring.c:2318
 __do_sys_io_uring_enter io_uring/io_uring.c:3390 [inline]
 __se_sys_io_uring_enter+0x409/0x4ce0 io_uring/io_uring.c:3325
 __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3325
 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: 22305 Comm: iou-wrk-22301 Not tainted 6.13.0-rc3-syzkaller-00193-ge9b8ffafd20a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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