Subject: Re: Re: KMSAN: uninit-value in kernel_sendmsg

From: syzbot <[email-masked]>
Date: Fri, 08 Nov 2019 08:15:14 -0800

> On Fri, Nov 8, 2019 at 4:54 PM syzbot
> <[email-masked]> wrote:

>> Hello,

>> syzbot found the following crash on:

>> HEAD commit:    124037e0 kmsan: drop inlines, rename  
>> do_kmsan_task_create()
>> git tree:       https://github.com/google/kmsan.git master
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1648eb9d600000
>> kernel config:   
>> https://syzkaller.appspot.com/x/.config?x=f03c659d0830ab8d
>> dashboard link:  
>> https://syzkaller.appspot.com/bug?extid=4b6f070bb7a8ea5420d4
>> compiler:       clang version 9.0.0 (/home/glider/llvm/clang
>> 80fee25776c2fb61e74c1ecb1a523375c2500b69)

>> Unfortunately, I don't have any reproducer for this crash yet.

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

> I think this is:

> #syz dup: KMSAN: use-after-free in rxrpc_send_keepalive

Can't dup bug to a bug in different reporting (upstream->moderation).Please  
dup syzbot bugs only onto syzbot bugs for the same kernel/reporting.

> https://syzkaller.appspot.com/bug?id=428e72dc175d0f4b23a1fb9b7d3d16fad7ef2a4b

>> =====================================================
>> BUG: KMSAN: uninit-value in rxrpc_send_keepalive+0x2fa/0x830
>> net/rxrpc/output.c:655
>> CPU: 0 PID: 3367 Comm: kworker/0:2 Not tainted 5.3.0-rc7+ #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Workqueue: krxrpcd rxrpc_peer_keepalive_worker
>> Call Trace:
>>    __dump_stack lib/dump_stack.c:77 [inline]
>>    dump_stack+0x191/0x1f0 lib/dump_stack.c:113
>>    kmsan_report+0x13a/0x2b0 mm/kmsan/kmsan_report.c:108
>>    __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:250
>>    sock_sendmsg_nosec net/socket.c:637 [inline]
>>    sock_sendmsg net/socket.c:657 [inline]
>>    kernel_sendmsg+0x2c9/0x440 net/socket.c:677
>>    rxrpc_send_keepalive+0x2fa/0x830 net/rxrpc/output.c:655
>>    rxrpc_peer_keepalive_dispatch net/rxrpc/peer_event.c:369 [inline]
>>    rxrpc_peer_keepalive_worker+0xb82/0x1510 net/rxrpc/peer_event.c:430
>>    process_one_work+0x1572/0x1ef0 kernel/workqueue.c:2269
>>    worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
>>    kthread+0x4b5/0x4f0 kernel/kthread.c:256
>>    ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355

>> Uninit was created at:
>>    kmsan_save_stack_with_flags mm/kmsan/kmsan.c:150 [inline]
>>    kmsan_internal_poison_shadow+0x53/0x100 mm/kmsan/kmsan.c:134
>>    kmsan_slab_alloc+0xaa/0x120 mm/kmsan/kmsan_hooks.c:103
>>    slab_alloc_node mm/slub.c:2790 [inline]
>>    slab_alloc mm/slub.c:2799 [inline]
>>    kmem_cache_alloc_trace+0x8c5/0xd20 mm/slub.c:2816
>>    kmalloc include/linux/slab.h:552 [inline]
>>    __hw_addr_create_ex net/core/dev_addr_lists.c:30 [inline]
>>    __hw_addr_add_ex net/core/dev_addr_lists.c:76 [inline]
>>    __hw_addr_add net/core/dev_addr_lists.c:84 [inline]
>>    dev_addr_init+0x152/0x700 net/core/dev_addr_lists.c:464
>>    alloc_netdev_mqs+0x2a9/0x1650 net/core/dev.c:9150
>>    rtnl_create_link+0x559/0x1190 net/core/rtnetlink.c:2931
>>    __rtnl_newlink net/core/rtnetlink.c:3186 [inline]
>>    rtnl_newlink+0x2757/0x38d0 net/core/rtnetlink.c:3254
>>    rtnetlink_rcv_msg+0x115a/0x1580 net/core/rtnetlink.c:5223
>>    netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2477
>>    rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:5241
>>    netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
>>    netlink_unicast+0xf6c/0x1050 net/netlink/af_netlink.c:1328
>>    netlink_sendmsg+0x110f/0x1330 net/netlink/af_netlink.c:1917
>>    sock_sendmsg_nosec net/socket.c:637 [inline]
>>    sock_sendmsg net/socket.c:657 [inline]
>>    ___sys_sendmsg+0x14ff/0x1590 net/socket.c:2311
>>    __sys_sendmsg net/socket.c:2356 [inline]
>>    __do_sys_sendmsg net/socket.c:2365 [inline]
>>    __se_sys_sendmsg+0x305/0x460 net/socket.c:2363
>>    __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2363
>>    do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:297
>>    entry_SYSCALL_64_after_hwframe+0x63/0xe7
>> =====================================================

>> ---
>> This bug is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at [email-masked].

>> syzbot will keep track of this bug report. See:
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