syzbot

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BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak in copy_to_user_iter lib/iov_iter.c:24 [inline]
BUG: KMSAN: kernel-infoleak in iterate_ubuf include/linux/iov_iter.h:30 [inline]
BUG: KMSAN: kernel-infoleak in iterate_and_advance2 include/linux/iov_iter.h:300 [inline]
BUG: KMSAN: kernel-infoleak in iterate_and_advance include/linux/iov_iter.h:328 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x2f3/0x2b30 lib/iov_iter.c:185
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 copy_to_user_iter lib/iov_iter.c:24 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:300 [inline]
 iterate_and_advance include/linux/iov_iter.h:328 [inline]
 _copy_to_iter+0x2f3/0x2b30 lib/iov_iter.c:185
 copy_page_to_iter+0x419/0x880 lib/iov_iter.c:362
 pipe_read+0x88c/0x21a0 fs/pipe.c:327
 new_sync_read fs/read_write.c:484 [inline]
 vfs_read+0xcdf/0xf50 fs/read_write.c:565
 ksys_read+0x240/0x4b0 fs/read_write.c:708
 __do_sys_read fs/read_write.c:717 [inline]
 __se_sys_read fs/read_write.c:715 [inline]
 __x64_sys_read+0x93/0xe0 fs/read_write.c:715
 x64_sys_call+0x314c/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:1
 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 stored to memory at:
 memcpy_to_iter lib/iov_iter.c:65 [inline]
 iterate_bvec include/linux/iov_iter.h:123 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:304 [inline]
 iterate_and_advance include/linux/iov_iter.h:328 [inline]
 _copy_to_iter+0xe5a/0x2b30 lib/iov_iter.c:185
 copy_page_to_iter+0x419/0x880 lib/iov_iter.c:362
 copy_folio_to_iter include/linux/uio.h:189 [inline]
 shmem_file_read_iter+0x860/0xf80 mm/shmem.c:3241
 do_iter_readv_writev+0x88a/0xa30
 vfs_iter_read+0x278/0x760 fs/read_write.c:909
 lo_read_simple drivers/block/loop.c:283 [inline]
 do_req_filebacked drivers/block/loop.c:516 [inline]
 loop_handle_cmd drivers/block/loop.c:1909 [inline]
 loop_process_work+0x2111/0x3760 drivers/block/loop.c:1944
 loop_workfn+0x48/0x60 drivers/block/loop.c:1968
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 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 stored to memory at:
 memcpy_from_iter lib/iov_iter.c:73 [inline]
 iterate_bvec include/linux/iov_iter.h:123 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:304 [inline]
 iterate_and_advance include/linux/iov_iter.h:328 [inline]
 __copy_from_iter lib/iov_iter.c:249 [inline]
 copy_page_from_iter_atomic+0x1299/0x30c0 lib/iov_iter.c:483
 copy_folio_from_iter_atomic include/linux/uio.h:201 [inline]
 generic_perform_write+0x8d1/0x1080 mm/filemap.c:4067
 shmem_file_write_iter+0x2ba/0x2f0 mm/shmem.c:3293
 do_iter_readv_writev+0x88a/0xa30
 vfs_iter_write+0x44d/0xd40 fs/read_write.c:974
 lo_write_bvec drivers/block/loop.c:243 [inline]
 lo_write_simple drivers/block/loop.c:264 [inline]
 do_req_filebacked drivers/block/loop.c:511 [inline]
 loop_handle_cmd drivers/block/loop.c:1909 [inline]
 loop_process_work+0x15fb/0x3760 drivers/block/loop.c:1944
 loop_workfn+0x48/0x60 drivers/block/loop.c:1968
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 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:
 __alloc_pages_noprof+0x9a7/0xe00 mm/page_alloc.c:4774
 alloc_pages_mpol_noprof+0x299/0x990 mm/mempolicy.c:2269
 alloc_pages_noprof mm/mempolicy.c:2348 [inline]
 folio_alloc_noprof+0x1db/0x310 mm/mempolicy.c:2355
 filemap_alloc_folio_noprof+0xa6/0x440 mm/filemap.c:1009
 __filemap_get_folio+0xac4/0x1550 mm/filemap.c:1951
 block_write_begin+0x6e/0x2b0 fs/buffer.c:2221
 exfat_write_begin+0xfb/0x400 fs/exfat/inode.c:434
 exfat_extend_valid_size fs/exfat/file.c:553 [inline]
 exfat_file_write_iter+0x771/0x12a0 fs/exfat/file.c:598
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0xb2b/0x1540 fs/read_write.c:679
 ksys_pwrite64 fs/read_write.c:786 [inline]
 __do_sys_pwrite64 fs/read_write.c:794 [inline]
 __se_sys_pwrite64 fs/read_write.c:791 [inline]
 __x64_sys_pwrite64+0x2c5/0x3b0 fs/read_write.c:791
 x64_sys_call+0xc16/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:19
 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

Bytes 0-1023 of 1024 are uninitialized
Memory access of size 1024 starts at ffff888013316000
Data copied to user address 000055557c6bc490

CPU: 1 UID: 0 PID: 5785 Comm: syz-executor Not tainted 6.13.0-rc2-syzkaller-00362-g2d8308bf5b67 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
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