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BUG: KMSAN: kernel-infoleak in copyout+0x1a4/0x250 lib/iov_iter.c:143
CPU: 1 PID: 18104 Comm: blkid Not tainted 4.20.0-rc3+ #106
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x32d/0x480 lib/dump_stack.c:113
 kmsan_report+0x12d/0x290 mm/kmsan/kmsan.c:683
 kmsan_internal_check_memory+0x9ce/0xa50 mm/kmsan/kmsan.c:769
 kmsan_copy_to_user+0x8d/0xa0 mm/kmsan/kmsan_hooks.c:634
 copyout+0x1a4/0x250 lib/iov_iter.c:143
 copy_page_to_iter_iovec lib/iov_iter.c:215 [inline]
 copy_page_to_iter+0x6d9/0x19b0 lib/iov_iter.c:853
 generic_file_buffered_read mm/filemap.c:2113 [inline]
 generic_file_read_iter+0x36df/0x5070 mm/filemap.c:2290
 blkdev_read_iter+0x20d/0x270 fs/block_dev.c:1936
 call_read_iter include/linux/fs.h:1851 [inline]
 new_sync_read fs/read_write.c:406 [inline]
 __vfs_read+0x874/0xb00 fs/read_write.c:418
 vfs_read+0x3b3/0x6f0 fs/read_write.c:452
 ksys_read fs/read_write.c:578 [inline]
 __do_sys_read fs/read_write.c:588 [inline]
 __se_sys_read+0x17a/0x370 fs/read_write.c:586
 __x64_sys_read+0x4a/0x70 fs/read_write.c:586
 do_syscall_64+0xcd/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x7fe0d22ce310
Code: 73 01 c3 48 8b 0d 28 4b 2b 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 83 3d e5 a2 2b 00 00 75 10 b8 00 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 6e 8a 01 00 48 89 04 24
RSP: 002b:00007fff3ff928d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe0d22ce310
RDX: 0000000000000100 RSI: 0000000001267df8 RDI: 0000000000000003
RBP: 0000000001267dd0 R08: 0000000000000028 R09: 0000000001680000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001267030
R13: 0000000000000100 R14: 0000000001267080 R15: 0000000001267de8

Uninit was created at:
 kmsan_save_stack_with_flags+0x7a/0x130 mm/kmsan/kmsan.c:246
 kmsan_internal_alloc_meta_for_pages+0x113/0x640 mm/kmsan/kmsan_hooks.c:102
 kmsan_alloc_page+0x77/0xc0 mm/kmsan/kmsan_hooks.c:402
 __alloc_pages_nodemask+0x171b/0x63b0 mm/page_alloc.c:4416
 alloc_pages_current+0x566/0x820 mm/mempolicy.c:2080
 alloc_pages include/linux/gfp.h:511 [inline]
 __page_cache_alloc+0xdb/0x4a0 mm/filemap.c:925
 page_cache_read mm/filemap.c:2313 [inline]
 filemap_fault+0x2530/0x2d80 mm/filemap.c:2497
 __do_fault mm/memory.c:2998 [inline]
 do_shared_fault mm/memory.c:3465 [inline]
 do_fault mm/memory.c:3540 [inline]
 handle_pte_fault mm/memory.c:3767 [inline]
 __handle_mm_fault mm/memory.c:3891 [inline]
 handle_mm_fault+0x4da5/0xa8b0 mm/memory.c:3928
 do_user_addr_fault arch/x86/mm/fault.c:1424 [inline]
 __do_page_fault+0xdd6/0x1d60 arch/x86/mm/fault.c:1490
 do_page_fault+0x7c/0xc0 arch/x86/mm/fault.c:1522
 page_fault+0x3d/0x50 arch/x86/entry/entry_64.S:1152
 __put_user_4+0x1c/0x30 arch/x86/lib/putuser.S:68
 block_ioctl+0x16f/0x1d0 fs/block_dev.c:1883
 do_vfs_ioctl+0xf36/0x2d30 fs/ioctl.c:46
 ksys_ioctl fs/ioctl.c:713 [inline]
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:718
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:718
 do_syscall_64+0xcd/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Bytes 0-255 of 256 are uninitialized
Memory access of size 256 starts at ffff88804cd62000
Data copied to user address 0000000001267df8
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