syzbot

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KMSAN: uninit-value in fuse_dev_do_write+0xaba/0xbd30 fs/fuse/dev.c:1840
CPU: 0 PID: 4465 Comm: syz-executor904 Not tainted 4.18.0-rc8+ #34
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+0x17c/0x1c0 lib/dump_stack.c:113
 kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:982
 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645
 fuse_dev_do_write+0xaba/0xbd30 fs/fuse/dev.c:1840
 fuse_dev_splice_write+0xe23/0xf90 fs/fuse/dev.c:2000
 do_splice_from fs/splice.c:852 [inline]
 direct_splice_actor+0x19e/0x200 fs/splice.c:1019
 splice_direct_to_actor+0x746/0xfb0 fs/splice.c:974
 do_splice_direct+0x332/0x540 fs/splice.c:1062
 do_sendfile+0x1090/0x1df0 fs/read_write.c:1440
 __do_sys_sendfile64 fs/read_write.c:1501 [inline]
 __se_sys_sendfile64+0x2ea/0x380 fs/read_write.c:1487
 __x64_sys_sendfile64+0x11e/0x170 fs/read_write.c:1487
 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x440069
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007fff423a6498 EFLAGS: 00000217 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440069
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000010000 R11: 0000000000000217 R12: 00000000004018f0
R13: 0000000000401980 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:271 [inline]
 kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573
 kmsan_memcpy_origins+0x13d/0x1b0 mm/kmsan/kmsan.c:397
 __msan_memcpy+0xda/0x130 mm/kmsan/kmsan_instr.c:432
 fuse_copy_do fs/fuse/dev.c:797 [inline]
 fuse_copy_one fs/fuse/dev.c:1023 [inline]
 fuse_dev_do_write+0x81a/0xbd30 fs/fuse/dev.c:1835
 fuse_dev_splice_write+0xe23/0xf90 fs/fuse/dev.c:2000
 do_splice_from fs/splice.c:852 [inline]
 direct_splice_actor+0x19e/0x200 fs/splice.c:1019
 splice_direct_to_actor+0x746/0xfb0 fs/splice.c:974
 do_splice_direct+0x332/0x540 fs/splice.c:1062
 do_sendfile+0x1090/0x1df0 fs/read_write.c:1440
 __do_sys_sendfile64 fs/read_write.c:1501 [inline]
 __se_sys_sendfile64+0x2ea/0x380 fs/read_write.c:1487
 __x64_sys_sendfile64+0x11e/0x170 fs/read_write.c:1487
 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline]
 kmsan_internal_alloc_meta_for_pages+0x146/0x700 mm/kmsan/kmsan.c:694
 kmsan_alloc_page+0x75/0xd0 mm/kmsan/kmsan_hooks.c:250
 __alloc_pages_nodemask+0xf6b/0x5c80 mm/page_alloc.c:4409
 alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
 alloc_pages include/linux/gfp.h:494 [inline]
 push_pipe+0x660/0xc10 lib/iov_iter.c:521
 __pipe_get_pages lib/iov_iter.c:1158 [inline]
 pipe_get_pages lib/iov_iter.c:1192 [inline]
 iov_iter_get_pages+0x1378/0x1810 lib/iov_iter.c:1203
 __bio_iov_iter_get_pages block/bio.c:924 [inline]
 bio_iov_iter_get_pages+0x1de/0xd90 block/bio.c:971
 __blkdev_direct_IO_simple fs/block_dev.c:222 [inline]
 blkdev_direct_IO+0x1fb6/0x2c70 fs/block_dev.c:432
 generic_file_read_iter+0x79a/0x4430 mm/filemap.c:2341
 blkdev_read_iter+0x20d/0x270 fs/block_dev.c:1934
 call_read_iter include/linux/fs.h:1787 [inline]
 generic_file_splice_read+0x629/0x960 fs/splice.c:308
 do_splice_to fs/splice.c:881 [inline]
 splice_direct_to_actor+0x4af/0xfb0 fs/splice.c:953
 do_splice_direct+0x332/0x540 fs/splice.c:1062
 do_sendfile+0x1090/0x1df0 fs/read_write.c:1440
 __do_sys_sendfile64 fs/read_write.c:1501 [inline]
 __se_sys_sendfile64+0x2ea/0x380 fs/read_write.c:1487
 __x64_sys_sendfile64+0x11e/0x170 fs/read_write.c:1487
 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
==================================================================