syzbot

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BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:121 [inline]
BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:156 [inline]
BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:231 [inline]
BUG: KMSAN: kernel-infoleak in __copy_page_to_iter lib/iov_iter.c:808 [inline]
BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0xa6b/0x2630 lib/iov_iter.c:836
 instrument_copy_to_user include/linux/instrumented.h:121 [inline]
 copyout lib/iov_iter.c:156 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:231 [inline]
 __copy_page_to_iter lib/iov_iter.c:808 [inline]
 copy_page_to_iter+0xa6b/0x2630 lib/iov_iter.c:836
 filemap_read+0xf11/0x1aa0 mm/filemap.c:2683
 generic_file_read_iter+0x190/0xa60 mm/filemap.c:2779
 blkdev_read_iter+0x2a6/0x380 block/fops.c:545
 call_read_iter include/linux/fs.h:2157 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x1631/0x1980 fs/read_write.c:485
 ksys_read+0x28c/0x520 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0xdb/0x120 fs/read_write.c:631
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Uninit was stored to memory at:
 _copy_to_iter+0x10d1/0x25c0 lib/iov_iter.c:623
 __copy_page_to_iter lib/iov_iter.c:811 [inline]
 copy_page_to_iter+0x188a/0x2630 lib/iov_iter.c:836
 shmem_file_read_iter+0xb7a/0x17f0 mm/shmem.c:2597
 do_iter_readv_writev+0xa7f/0xc70
 do_iter_read+0x52c/0x14c0 fs/read_write.c:790
 vfs_iter_read+0x118/0x180 fs/read_write.c:832
 lo_read_simple drivers/block/loop.c:404 [inline]
 do_req_filebacked drivers/block/loop.c:675 [inline]
 loop_handle_cmd drivers/block/loop.c:2201 [inline]
 loop_process_work+0x3e32/0x5590 drivers/block/loop.c:2241
 loop_rootcg_workfn+0x54/0x60 drivers/block/loop.c:2272
 process_one_work+0xdc7/0x1760 kernel/workqueue.c:2297
 worker_thread+0x1101/0x22b0 kernel/workqueue.c:2444
 kthread+0x66b/0x780 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

Uninit was stored to memory at:
 copy_page_from_iter_atomic+0x14dd/0x2a80 lib/iov_iter.c:925
 generic_perform_write+0x58d/0xc80 mm/filemap.c:3778
 __generic_file_write_iter+0x573/0xc00 mm/filemap.c:3897
 generic_file_write_iter+0x16f/0x440 mm/filemap.c:3929
 do_iter_readv_writev+0xa7f/0xc70
 do_iter_write+0x52c/0x1500 fs/read_write.c:855
 vfs_iter_write+0x118/0x180 fs/read_write.c:896
 lo_write_bvec+0x2e5/0x920 drivers/block/loop.c:328
 lo_write_simple drivers/block/loop.c:350 [inline]
 do_req_filebacked drivers/block/loop.c:668 [inline]
 loop_handle_cmd drivers/block/loop.c:2201 [inline]
 loop_process_work+0x4935/0x5590 drivers/block/loop.c:2241
 loop_rootcg_workfn+0x54/0x60 drivers/block/loop.c:2272
 process_one_work+0xdc7/0x1760 kernel/workqueue.c:2297
 worker_thread+0x1101/0x22b0 kernel/workqueue.c:2444
 kthread+0x66b/0x780 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

Uninit was created at:
 __alloc_pages+0x8b3/0xfb0 mm/page_alloc.c:5421
 alloc_pages+0xa39/0xde0 mm/mempolicy.c:2191
 __page_cache_alloc mm/filemap.c:1022 [inline]
 pagecache_get_page+0x1384/0x1ec0 mm/filemap.c:1940
 find_or_create_page include/linux/pagemap.h:420 [inline]
 grow_dev_page+0x1b1/0xe00 fs/buffer.c:949
 grow_buffers fs/buffer.c:1014 [inline]
 __getblk_slow fs/buffer.c:1041 [inline]
 __getblk_gfp+0x437/0x670 fs/buffer.c:1334
 sb_getblk include/linux/buffer_head.h:327 [inline]
 ext4_getblk+0x438/0xed0 fs/ext4/inode.c:854
 ext4_xattr_inode_write fs/ext4/xattr.c:1368 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1532 [inline]
 ext4_xattr_set_entry+0x6161/0x7210 fs/ext4/xattr.c:1656
 ext4_xattr_ibody_set+0x151/0x490 fs/ext4/xattr.c:2210
 ext4_xattr_set_handle+0x1c49/0x2cd0 fs/ext4/xattr.c:2367
 ext4_xattr_set+0x49c/0x6e0 fs/ext4/xattr.c:2480
 ext4_xattr_trusted_set+0xef/0x100 fs/ext4/xattr_trusted.c:38
 __vfs_setxattr+0x94c/0x9a0 fs/xattr.c:180
 __vfs_setxattr_noperm+0x35d/0xe10 fs/xattr.c:214
 __vfs_setxattr_locked+0x629/0x690 fs/xattr.c:275
 vfs_setxattr+0x446/0x7c0 fs/xattr.c:301
 setxattr+0x422/0x7b0 fs/xattr.c:575
 path_setxattr+0x305/0x530 fs/xattr.c:595
 __do_sys_setxattr fs/xattr.c:611 [inline]
 __se_sys_setxattr fs/xattr.c:607 [inline]
 __ia32_sys_setxattr+0x15b/0x1c0 fs/xattr.c:607
 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
 __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Bytes 1-4095 of 4096 are uninitialized
Memory access of size 4096 starts at ffff888171cf3000
Data copied to user address 00005634b5eae628
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