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    SubjectRe: KMSAN: uninit-value in kernel_sendmsg
    On Fri, Nov 8, 2019 at 4:54 PM syzbot
    <syzbot+4b6f070bb7a8ea5420d4@syzkaller.appspotmail.com> 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: syzbot+4b6f070bb7a8ea5420d4@syzkaller.appspotmail.com

    I think this is:

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

    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 syzkaller@googlegroups.com.
    >
    > syzbot will keep track of this bug report. See:
    > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
    >
    > --
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