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BUG: KMSAN: kernel-infoleak in kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
CPU: 1 PID: 19158 Comm: syz-executor.4 Not tainted 5.9.0-rc4-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+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:122
 kmsan_internal_check_memory+0x358/0x3d0 mm/kmsan/kmsan.c:459
 kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
 instrument_copy_to_user include/linux/instrumented.h:91 [inline]
 copyout lib/iov_iter.c:143 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:216 [inline]
 copy_page_to_iter+0xad8/0x2260 lib/iov_iter.c:925
 pipe_read+0x97f/0x22c0 fs/pipe.c:309
 call_read_iter include/linux/fs.h:1876 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x136b/0x1590 fs/read_write.c:481
 ksys_read+0x275/0x500 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read+0x92/0xb0 fs/read_write.c:615
 __ia32_sys_read+0x4a/0x70 fs/read_write.c:615
 do_syscall_32_irqs_on arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x129/0x180 arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7f69549
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f55630cc EFLAGS: 00000296 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000100
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:143
 kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:268 [inline]
 kmsan_alloc_page+0xc5/0x1a0 mm/kmsan/kmsan_shadow.c:292
 __alloc_pages_nodemask+0xf34/0x1120 mm/page_alloc.c:4927
 alloc_pages_current+0x685/0xb50 mm/mempolicy.c:2275
 alloc_pages include/linux/gfp.h:545 [inline]
 push_pipe+0x73d/0xcd0 lib/iov_iter.c:538
 __pipe_get_pages lib/iov_iter.c:1279 [inline]
 pipe_get_pages_alloc lib/iov_iter.c:1386 [inline]
 iov_iter_get_pages_alloc+0x210e/0x26b0 lib/iov_iter.c:1404
 default_file_splice_read+0x2dd/0x1590 fs/splice.c:385
 do_splice_to fs/splice.c:871 [inline]
 do_splice+0x36d2/0x39e0 fs/splice.c:1179
 __do_sys_splice fs/splice.c:1419 [inline]
 __se_sys_splice+0x323/0x500 fs/splice.c:1401
 __ia32_sys_splice+0x6e/0x90 fs/splice.c:1401
 do_syscall_32_irqs_on arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x129/0x180 arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Byte 0 of 1 is uninitialized
Memory access of size 1 starts at ffff888103087000
Data copied to user address 0000000020000100
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