KMSAN: uninit-value in path_openat

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    f0d5ec90 kmsan: apply __no_sanitize_memory to dotraplinkag..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=159636b7100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=86e4f8af239686c6
dashboard link: https://syzkaller.appspot.com/bug?extid=4191a44ad556eacc1a7a
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1073c0bd100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13974b2f100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4191a44ad556eacc1a7a@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in may_create_in_sticky fs/namei.c:1060 [inline]
BUG: KMSAN: uninit-value in do_open fs/namei.c:3207 [inline]
BUG: KMSAN: uninit-value in path_openat+0x48be/0x5d50 fs/namei.c:3346
CPU: 1 PID: 8815 Comm: syz-executor333 Not tainted 5.7.0-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+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 may_create_in_sticky fs/namei.c:1060 [inline]
 do_open fs/namei.c:3207 [inline]
 path_openat+0x48be/0x5d50 fs/namei.c:3346
 do_file_open_root+0x469/0xb40 fs/namei.c:3401
 file_open_root+0x6f1/0x760 fs/open.c:1128
 do_handle_open+0xa11/0xe30 fs/fhandle.c:232
 __do_compat_sys_open_by_handle_at fs/fhandle.c:277 [inline]
 __se_compat_sys_open_by_handle_at+0x8e/0xa0 fs/fhandle.c:274
 __ia32_compat_sys_open_by_handle_at+0x4a/0x70 fs/fhandle.c:274
 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
 do_fast_syscall_32+0x3bf/0x6d0 arch/x86/entry/common.c:398
 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f3bdd9
Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 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:00000000ff8507fc EFLAGS: 00000207 ORIG_RAX: 0000000000000156
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 0000000020000200
RDX: 0000000000002f40 RSI: 0000000000000001 RDI: 00000000080bb4c8
RBP: 0000000000000012 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Local variable ----nd@do_file_open_root created at:
 do_file_open_root+0xa4/0xb40 fs/namei.c:3385
 do_file_open_root+0xa4/0xb40 fs/namei.c:3385
=====================================================


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