KMSAN: uninit-value in from

KMSAN: uninit-value in from_kuid
Status: upstream: reported on 2021/11/27 15:50
Reported-by: syzbot+dfac92a50024b54acaa4@syzkaller.appspotmail.com
Fix commit: 3cb6ee991496 9p: only copy valid iattrs in 9P2000.L setattr implementation
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu2-riscv64 ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386]
First crash: 66d, last: 18d

Sample crash report:

=====================================================
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
 vfs_utimes+0x8a0/0xc50 fs/utimes.c:65
 do_utimes_path fs/utimes.c:98 [inline]
 do_utimes fs/utimes.c:144 [inline]
 __do_sys_utime32 fs/utimes.c:247 [inline]
 __se_sys_utime32+0x37c/0x510 fs/utimes.c:235
 __ia32_sys_utime32+0x91/0xc0 fs/utimes.c:235
 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
 vfs_utimes+0x8a0/0xc50 fs/utimes.c:65
 do_utimes_path fs/utimes.c:98 [inline]
 do_utimes fs/utimes.c:144 [inline]
 __do_sys_utime32 fs/utimes.c:247 [inline]
 __se_sys_utime32+0x37c/0x510 fs/utimes.c:235
 __ia32_sys_utime32+0x91/0xc0 fs/utimes.c:235
 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:
 vfs_utimes+0x69/0xc50 fs/utimes.c:22
 do_utimes_path fs/utimes.c:98 [inline]
 do_utimes fs/utimes.c:144 [inline]
 __do_sys_utime32 fs/utimes.c:247 [inline]
 __se_sys_utime32+0x37c/0x510 fs/utimes.c:235

CPU: 0 PID: 4932 Comm: syz-executor.3 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================

Crashes (7):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci-upstream-kmsan-gce-386	2022/01/09 10:04	https://github.com/google/kmsan.git master	81c325bbf94e	2ca0d385	.config	log	report	info	KMSAN: uninit-value in from_kuid
ci-upstream-kmsan-gce-386	2022/01/01 03:47	https://github.com/google/kmsan.git master	81c325bbf94e	e1768e9c	.config	log	report	info	KMSAN: uninit-value in from_kuid
ci-upstream-kmsan-gce-386	2021/12/31 10:54	https://github.com/google/kmsan.git master	81c325bbf94e	36bd2e48	.config	log	report	info	KMSAN: uninit-value in from_kuid
ci-upstream-kmsan-gce-386	2021/12/15 11:17	https://github.com/google/kmsan.git master	d1daf229a313	f752fb53	.config	log	report	info	KMSAN: uninit-value in from_kuid
ci-upstream-kmsan-gce-386	2021/12/10 09:12	https://github.com/google/kmsan.git master	8b936c96768e	4d4ce9bc	.config	log	report	info	KMSAN: uninit-value in from_kuid
ci-upstream-kmsan-gce-386	2021/12/08 02:12	https://github.com/google/kmsan.git master	8b936c96768e	0230ba3e	.config	log	report	info	KMSAN: uninit-value in from_kuid
ci-upstream-kmsan-gce-386	2021/11/22 10:36	https://github.com/google/kmsan.git master	425295055ce6	4eb20a4e	.config	log	report	info	KMSAN: uninit-value in from_kuid