syzbot

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BUG: KMSAN: uninit-value in save_stack_address arch/x86/kernel/stacktrace.c:21 [inline]
BUG: KMSAN: uninit-value in __save_stack_trace+0x5b2/0xa80 arch/x86/kernel/stacktrace.c:46
CPU: 1 PID: 3537 Comm: syzkaller846494 Not tainted 4.16.0+ #82
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:53
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
 save_stack_address arch/x86/kernel/stacktrace.c:21 [inline]
 __save_stack_trace+0x5b2/0xa80 arch/x86/kernel/stacktrace.c:46
 save_stack_trace+0xa5/0xf0 arch/x86/kernel/stacktrace.c:60
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:293 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684
 kmsan_memcpy_origins+0x11d/0x170 mm/kmsan/kmsan.c:526
 kmsan_copy_to_user+0x132/0x160 mm/kmsan/kmsan.c:1211
 copy_to_user include/linux/uaccess.h:184 [inline]
 seq_read+0x1cc9/0x2260 fs/seq_file.c:282
 do_loop_readv_writev fs/read_write.c:673 [inline]
 do_iter_read+0x880/0xd70 fs/read_write.c:897
 vfs_readv+0x1ec/0x260 fs/read_write.c:959
 kernel_readv fs/splice.c:361 [inline]
 default_file_splice_read+0xa9a/0x1120 fs/splice.c:416
 do_splice_to fs/splice.c:880 [inline]
 splice_direct_to_actor+0x4c6/0x1040 fs/splice.c:952
 do_splice_direct+0x335/0x540 fs/splice.c:1061
 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413
 SYSC_sendfile64+0x1b3/0x300 fs/read_write.c:1468
 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x4401d9
RSP: 002b:00007fff435d8938 EFLAGS: 00000217 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401d9
RDX: 0000000020a2effc RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00000000006ca018 R08: 65732f636f72702f R09: 65732f636f72702f
R10: 0000000000001000 R11: 0000000000000217 R12: 0000000000401a60
R13: 0000000000401af0 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:293 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684
 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:521
 save_stack_trace+0xe4/0xf0 arch/x86/kernel/stacktrace.c:59
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:293 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684
 kmsan_memcpy_origins+0x11d/0x170 mm/kmsan/kmsan.c:526
 kmsan_copy_to_user+0x132/0x160 mm/kmsan/kmsan.c:1211
 copy_to_user include/linux/uaccess.h:184 [inline]
 seq_read+0x1cc9/0x2260 fs/seq_file.c:282
 do_loop_readv_writev fs/read_write.c:673 [inline]
 do_iter_read+0x880/0xd70 fs/read_write.c:897
 vfs_readv+0x1ec/0x260 fs/read_write.c:959
 kernel_readv fs/splice.c:361 [inline]
 default_file_splice_read+0xa9a/0x1120 fs/splice.c:416
 do_splice_to fs/splice.c:880 [inline]
 splice_direct_to_actor+0x4c6/0x1040 fs/splice.c:952
 do_splice_direct+0x335/0x540 fs/splice.c:1061
 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413
 SYSC_sendfile64+0x1b3/0x300 fs/read_write.c:1468
 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
Local variable description: ----flags.i.i.i@rcu_all_qs
Variable was created at:
 rcu_all_qs+0x32/0x1f0 kernel/rcu/tree.c:478
 _cond_resched+0x3c/0xd0 kernel/sched/core.c:4935
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