=====================================================
BUG: KMSAN: uninit-value in map_id_up_base kernel/user_namespace.c:335 [inline]
BUG: KMSAN: uninit-value in map_id_up kernel/user_namespace.c:365 [inline]
BUG: KMSAN: uninit-value in from_kuid+0x51d/0xbd0 kernel/user_namespace.c:413
 map_id_up_base kernel/user_namespace.c:335 [inline]
 map_id_up kernel/user_namespace.c:365 [inline]
 from_kuid+0x51d/0xbd0 kernel/user_namespace.c:413
 p9pdu_vwritef+0x15aa/0x5100 net/9p/protocol.c:398
 p9pdu_writef+0x240/0x290 net/9p/protocol.c:539
 p9pdu_vwritef+0x21ed/0x5100 net/9p/protocol.c:490
 p9_client_prepare_req+0xe64/0x16d0 net/9p/client.c:703
 p9_client_rpc+0x28b/0x1460 net/9p/client.c:734
 p9_client_setattr+0x113/0x2c0 net/9p/client.c:1894
 v9fs_vfs_setattr_dotl+0x7e2/0xd70 fs/9p/vfs_inode_dotl.c:588
 notify_change+0x1fde/0x2180 fs/attr.c:410
 chmod_common+0x3fb/0x7b0 fs/open.c:581
 do_fchmodat fs/open.c:620 [inline]
 __do_sys_chmod fs/open.c:638 [inline]
 __se_sys_chmod fs/open.c:636 [inline]
 __ia32_sys_chmod+0x185/0x2d0 fs/open.c:636
 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
 __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Uninit was stored to memory at:
 v9fs_vfs_setattr_dotl+0x58a/0xd70 fs/9p/vfs_inode_dotl.c:565
 notify_change+0x1fde/0x2180 fs/attr.c:410
 chmod_common+0x3fb/0x7b0 fs/open.c:581
 do_fchmodat fs/open.c:620 [inline]
 __do_sys_chmod fs/open.c:638 [inline]
 __se_sys_chmod fs/open.c:636 [inline]
 __ia32_sys_chmod+0x185/0x2d0 fs/open.c:636
 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
 __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Local variable newattrs created at:
 chmod_common+0x102/0x7b0 fs/open.c:568
 do_fchmodat fs/open.c:620 [inline]
 __do_sys_chmod fs/open.c:638 [inline]
 __se_sys_chmod fs/open.c:636 [inline]
 __ia32_sys_chmod+0x185/0x2d0 fs/open.c:636

CPU: 1 PID: 10383 Comm: syz-executor.4 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================