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BUG: KMSAN: uninit-value in copyout lib/iov_iter.c:140 [inline]
BUG: KMSAN: uninit-value in copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
BUG: KMSAN: uninit-value in copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
CPU: 0 PID: 8534 Comm: syz-executor7 Not tainted 4.17.0-rc5+ #103
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+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x149/0x260 mm/kmsan/kmsan.c:1084
 kmsan_internal_check_memory+0x179/0x1e0 mm/kmsan/kmsan.c:1196
 kmsan_copy_to_user+0x75/0x160 mm/kmsan/kmsan.c:1219
 copyout lib/iov_iter.c:140 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
 copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
 generic_file_buffered_read mm/filemap.c:2185 [inline]
 generic_file_read_iter+0x2fa5/0x44e0 mm/filemap.c:2362
 do_iter_readv_writev+0x84d/0xa00 include/linux/fs.h:1778
 do_iter_read+0x303/0xd70 fs/read_write.c:922
 vfs_readv fs/read_write.c:986 [inline]
 do_preadv+0x3a1/0x580 fs/read_write.c:1070
 __do_sys_preadv fs/read_write.c:1120 [inline]
 __se_sys_preadv fs/read_write.c:1115 [inline]
 __x64_sys_preadv+0x120/0x170 fs/read_write.c:1115
 do_syscall_64+0x152/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x455a09
RSP: 002b:00007fb794d64c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007fb794d656d4 RCX: 0000000000455a09
RDX: 0000000000000001 RSI: 0000000020000380 RDI: 0000000000000014
RBP: 000000000072bf50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000054e R14: 00000000006fcff0 R15: 0000000000000001

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:815
 kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:885
 __alloc_pages_nodemask+0xfc0/0x5dc0 mm/page_alloc.c:4402
 alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
 alloc_pages include/linux/gfp.h:494 [inline]
 __page_cache_alloc+0x95/0x320 mm/filemap.c:946
 page_cache_alloc include/linux/pagemap.h:234 [inline]
 generic_file_buffered_read mm/filemap.c:2273 [inline]
 generic_file_read_iter+0xd36/0x44e0 mm/filemap.c:2362
 do_iter_readv_writev+0x84d/0xa00 include/linux/fs.h:1778
 do_iter_read+0x303/0xd70 fs/read_write.c:922
 vfs_readv fs/read_write.c:986 [inline]
 do_preadv+0x3a1/0x580 fs/read_write.c:1070
 __do_sys_preadv fs/read_write.c:1120 [inline]
 __se_sys_preadv fs/read_write.c:1115 [inline]
 __x64_sys_preadv+0x120/0x170 fs/read_write.c:1115
 do_syscall_64+0x152/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Bytes 0-4095 of 4096 are uninitialized
Memory access starts at ffff88012d8d7000
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