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BUG: KMSAN: uninit-value in kmsan_check_memory+0xd/0x10 mm/kmsan/kmsan_hooks.c:428
CPU: 0 PID: 11586 Comm: syz-executor.0 Not tainted 5.8.0-rc5-syzkaller #0
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+0x1df/0x240 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
 kmsan_internal_check_memory+0x358/0x3d0 mm/kmsan/kmsan.c:457
 kmsan_check_memory+0xd/0x10 mm/kmsan/kmsan_hooks.c:428
 instrument_copy_to_user include/linux/instrumented.h:91 [inline]
 copyout lib/iov_iter.c:142 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:215 [inline]
 copy_page_to_iter+0x7b4/0x1bb0 lib/iov_iter.c:924
 pipe_read+0x6a6/0x1a00 fs/pipe.c:309
 call_read_iter include/linux/fs.h:1902 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0xc67/0x1230 fs/read_write.c:481
 ksys_read+0x267/0x450 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read+0x92/0xb0 fs/read_write.c:615
 __x64_sys_read+0x4a/0x70 fs/read_write.c:615
 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1d9
Code: Bad RIP value.
RSP: 002b:00007fd3eccf1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000000240c0 RCX: 000000000045c1d9
RDX: 0000000000000002 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 0000000000c9fb6f R14: 00007fd3eccf29c0 R15: 000000000078bf0c

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:144
 kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:269 [inline]
 kmsan_alloc_page+0xb9/0x180 mm/kmsan/kmsan_shadow.c:293
 __alloc_pages_nodemask+0x56a2/0x5dc0 mm/page_alloc.c:4889
 alloc_pages_current+0x672/0x990 mm/mempolicy.c:2292
 alloc_pages include/linux/gfp.h:545 [inline]
 push_pipe+0x605/0xb70 lib/iov_iter.c:537
 __pipe_get_pages lib/iov_iter.c:1278 [inline]
 pipe_get_pages_alloc lib/iov_iter.c:1385 [inline]
 iov_iter_get_pages_alloc+0x18a9/0x21c0 lib/iov_iter.c:1403
 default_file_splice_read fs/splice.c:385 [inline]
 do_splice_to+0x4fc/0x14f0 fs/splice.c:871
 do_splice+0x2ccd/0x30a0 fs/splice.c:1179
 __do_sys_splice fs/splice.c:1419 [inline]
 __se_sys_splice+0x271/0x420 fs/splice.c:1401
 __x64_sys_splice+0x6e/0x90 fs/splice.c:1401
 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Bytes 0-1 of 2 are uninitialized
Memory access of size 2 starts at ffffa3b0c1437000
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