=====================================================
BUG: KMSAN: uninit-value in check_copy_size include/linux/thread_info.h:233 [inline]
BUG: KMSAN: uninit-value in copy_from_iter include/linux/uio.h:168 [inline]
BUG: KMSAN: uninit-value in copy_from_iter_full include/linux/uio.h:177 [inline]
BUG: KMSAN: uninit-value in pdu_write_u net/9p/protocol.c:68 [inline]
BUG: KMSAN: uninit-value in p9pdu_vwritef+0x457a/0x4cf0 net/9p/protocol.c:439
 check_copy_size include/linux/thread_info.h:233 [inline]
 copy_from_iter include/linux/uio.h:168 [inline]
 copy_from_iter_full include/linux/uio.h:177 [inline]
 pdu_write_u net/9p/protocol.c:68 [inline]
 p9pdu_vwritef+0x457a/0x4cf0 net/9p/protocol.c:439
 p9_client_prepare_req+0xf0a/0x1710 net/9p/client.c:703
 p9_client_rpc+0x295/0x14a0 net/9p/client.c:734
 p9_client_write+0x670/0xf70 net/9p/client.c:1667
 v9fs_fid_xattr_set+0x3aa/0x530 fs/9p/xattr.c:130
 v9fs_xattr_set fs/9p/xattr.c:100 [inline]
 v9fs_xattr_handler_set+0x1b8/0x220 fs/9p/xattr.c:159
 __vfs_setxattr+0x8d4/0x920 fs/xattr.c:180
 __vfs_setxattr_noperm+0x38c/0xe80 fs/xattr.c:214
 __vfs_setxattr_locked+0x627/0x690 fs/xattr.c:275
 vfs_setxattr+0x444/0x7b0 fs/xattr.c:301
 setxattr+0x43a/0x800 fs/xattr.c:576
 path_setxattr+0x30e/0x540 fs/xattr.c:596
 __do_sys_setxattr fs/xattr.c:612 [inline]
 __se_sys_setxattr fs/xattr.c:608 [inline]
 __ia32_sys_setxattr+0x15f/0x1c0 fs/xattr.c:608
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0x95/0xf0 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:754 [inline]
 slab_alloc_node mm/slub.c:3231 [inline]
 slab_alloc mm/slub.c:3239 [inline]
 kmem_cache_alloc_trace+0xa8e/0x10f0 mm/slub.c:3270
 kmalloc include/linux/slab.h:581 [inline]
 p9_fid_create+0x81/0x470 net/9p/client.c:892
 p9_client_walk+0x161/0xe30 net/9p/client.c:1180
 clone_fid fs/9p/fid.h:21 [inline]
 v9fs_fid_xattr_set+0x248/0x530 fs/9p/xattr.c:118
 v9fs_xattr_set fs/9p/xattr.c:100 [inline]
 v9fs_xattr_handler_set+0x1b8/0x220 fs/9p/xattr.c:159
 __vfs_setxattr+0x8d4/0x920 fs/xattr.c:180
 __vfs_setxattr_noperm+0x38c/0xe80 fs/xattr.c:214
 __vfs_setxattr_locked+0x627/0x690 fs/xattr.c:275
 vfs_setxattr+0x444/0x7b0 fs/xattr.c:301
 setxattr+0x43a/0x800 fs/xattr.c:576
 path_setxattr+0x30e/0x540 fs/xattr.c:596
 __do_sys_setxattr fs/xattr.c:612 [inline]
 __se_sys_setxattr fs/xattr.c:608 [inline]
 __ia32_sys_setxattr+0x15f/0x1c0 fs/xattr.c:608
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0x95/0xf0 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

CPU: 0 PID: 14039 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-16253-g2f3064574275 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================