Subject: Re: [syzbot] [net?] [nfc?] KMSAN: uninit-value in nci_dev_up

From: syzbot <[email-masked]>
Date: Thu, 25 Jan 2024 08:23:28 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    9f8413c4a66f Merge tag 'cgroup-for-6.8' of git://git.kerne..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12c59927e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=656820e61b758b15
dashboard link: https://syzkaller.appspot.com/bug?extid=7ea9413ea6749baf5574
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=153e178be80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10a6c1e3e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/79d9f2f4b065/disk-9f8413c4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cbc68430d9c6/vmlinux-9f8413c4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9740ad9fc172/bzImage-9f8413c4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

=====================================================
BUG: KMSAN: uninit-value in nci_init_req net/nfc/nci/core.c:177 [inline]
BUG: KMSAN: uninit-value in __nci_request net/nfc/nci/core.c:108 [inline]
BUG: KMSAN: uninit-value in nci_open_device net/nfc/nci/core.c:521 [inline]
BUG: KMSAN: uninit-value in nci_dev_up+0xfec/0x1b10 net/nfc/nci/core.c:632
 nci_init_req net/nfc/nci/core.c:177 [inline]
 __nci_request net/nfc/nci/core.c:108 [inline]
 nci_open_device net/nfc/nci/core.c:521 [inline]
 nci_dev_up+0xfec/0x1b10 net/nfc/nci/core.c:632
 nfc_dev_up+0x26e/0x440 net/nfc/core.c:118
 nfc_genl_dev_up+0xfe/0x1d0 net/nfc/netlink.c:770
 genl_family_rcv_msg_doit net/netlink/genetlink.c:972 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:1052 [inline]
 genl_rcv_msg+0x11ec/0x1290 net/netlink/genetlink.c:1067
 netlink_rcv_skb+0x371/0x650 net/netlink/af_netlink.c:2545
 genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076
 netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
 netlink_unicast+0xf47/0x1250 net/netlink/af_netlink.c:1368
 netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was stored to memory at:
 nci_core_reset_ntf_packet net/nfc/nci/ntf.c:36 [inline]
 nci_ntf_packet+0x19dc/0x39c0 net/nfc/nci/ntf.c:782
 nci_rx_work+0x213/0x500 net/nfc/nci/core.c:1522
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2706
 worker_thread+0xf45/0x1490 kernel/workqueue.c:2787
 kthread+0x3ed/0x540 kernel/kthread.c:388
 ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

Uninit was created at:
 slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
 slab_alloc_node mm/slub.c:3478 [inline]
 kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
 __alloc_skb+0x318/0x740 net/core/skbuff.c:651
 alloc_skb include/linux/skbuff.h:1286 [inline]
 virtual_ncidev_write+0x6d/0x280 drivers/nfc/virtual_ncidev.c:120
 vfs_write+0x48b/0x1200 fs/read_write.c:588
 ksys_write+0x20f/0x4c0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x93/0xd0 fs/read_write.c:652
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

CPU: 1 PID: 5012 Comm: syz-executor935 Not tainted 6.7.0-syzkaller-00562-g9f8413c4a66f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
=====================================================

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#syz test: git://repo/address.git branch-or-commit-hash
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