KMSAN: uninit-value in p9pdu

KMSAN: uninit-value in p9pdu_vwritef
Status: upstream: reported on 2022/01/07 12:50
Reported-by: syzbot+99f920ef970b8c366bfe@syzkaller.appspotmail.com
First crash: 41d, last: 2d14h

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KMSAN: kernel-infoleak in _copy_to_iter (6)	C			463	4h08m	49d	19/22	internal: reported C repro on 2021/12/09 13:48

Sample crash report:

=====================================================
BUG: KMSAN: uninit-value in p9pdu_vwritef+0x14a7/0x5100 net/9p/protocol.c:386
 p9pdu_vwritef+0x14a7/0x5100 net/9p/protocol.c:386
 p9_client_prepare_req+0xe64/0x16d0 net/9p/client.c:703
 p9_client_rpc+0x28b/0x1460 net/9p/client.c:734
 p9_client_attach+0x2e1/0xac0 net/9p/client.c:1132
 v9fs_session_init+0x277d/0x2cd0 fs/9p/v9fs.c:457
 v9fs_mount+0x146/0x1460 fs/9p/vfs_super.c:125
 legacy_get_tree+0x163/0x2e0 fs/fs_context.c:610
 vfs_get_tree+0xd8/0x5d0 fs/super.c:1500
 do_new_mount+0x7b5/0x16f0 fs/namespace.c:2988
 path_mount+0x1021/0x28b0 fs/namespace.c:3318
 do_mount fs/namespace.c:3331 [inline]
 __do_sys_mount fs/namespace.c:3539 [inline]
 __se_sys_mount+0x8a8/0x9d0 fs/namespace.c:3516
 __ia32_sys_mount+0x157/0x1b0 fs/namespace.c:3516
 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 handle.i created at:
 perf_log_itrace_start kernel/events/core.c:9068 [inline]
 event_sched_in+0x1312/0x35c0 kernel/events/core.c:2557
 group_sched_in kernel/events/core.c:2595 [inline]
 merge_sched_in kernel/events/core.c:3746 [inline]
 visit_groups_merge+0x2919/0x7460 kernel/events/core.c:3696

CPU: 0 PID: 28120 Comm: syz-executor.1 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================

Crashes (13):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci-upstream-kmsan-gce-386	2022/01/25 06:01	https://github.com/google/kmsan.git master	85cfd6e539bd	2cbffd88	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2022/01/21 20:43	https://github.com/google/kmsan.git master	85cfd6e539bd	214351e1	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2022/01/10 03:07	https://github.com/google/kmsan.git master	81c325bbf94e	2ca0d385	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2022/01/07 22:53	https://github.com/google/kmsan.git master	81c325bbf94e	2ca0d385	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2022/01/04 18:44	https://github.com/google/kmsan.git master	81c325bbf94e	0a2584dd	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2022/01/04 17:59	https://github.com/google/kmsan.git master	81c325bbf94e	0a2584dd	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2021/12/31 19:16	https://github.com/google/kmsan.git master	81c325bbf94e	e1768e9c	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2021/12/29 10:27	https://github.com/google/kmsan.git master	81c325bbf94e	76c8cf06	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2021/12/28 02:08	https://github.com/google/kmsan.git master	81c325bbf94e	6b3c5e64	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2021/12/27 18:22	https://github.com/google/kmsan.git master	81c325bbf94e	5140bd58	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2021/12/22 08:34	https://github.com/google/kmsan.git master	81c325bbf94e	6caa12e4	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2021/12/17 11:06	https://github.com/google/kmsan.git master	b0a8b5053e8b	44068e19	.config	log	report	info	KMSAN: uninit-value in p9pdu_vwritef
ci-upstream-kmsan-gce-386	2022/01/24 17:37	https://github.com/google/kmsan.git master	85cfd6e539bd	214351e1	.config	log	report	info	KMSAN: uninit-value in p9_client_write