On Thu, Oct 1, 2020 at 12:29 PM syzbot syzbot+da9194708de785081f11@syzkaller.appspotmail.com wrote:
Hello,
syzbot found the following issue on:
HEAD commit: 5edb1df2 kmsan: drop the _nosanitize string functions git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=10cc55a7900000 kernel config: https://syzkaller.appspot.com/x/.config?x=4991d22eb136035c dashboard link: https://syzkaller.appspot.com/bug?extid=da9194708de785081f11 compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
Unfortunately, I don't have any reproducer for this issue yet.
IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+da9194708de785081f11@syzkaller.appspotmail.com
It's somewhat unobvious how this can happen (or not?).
But may be related to: INFO: rcu detected stall in batadv_nc_worker (3) https://syzkaller.appspot.com/bug?id=6dba9b6476dd536c17afa799a72f265e448ff82...
which happens with low frequency for the past 300 days, 21 stalls in total.
If we imagine the list somehow ends up uninitialized, occasional infinite loops make perfect sense.
===================================================== BUG: KMSAN: uninit-value in batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline] BUG: KMSAN: uninit-value in batadv_nc_worker+0x1c0/0x1d70 net/batman-adv/network-coding.c:718 CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.9.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x21c/0x280 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:122 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:201 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline] batadv_nc_worker+0x1c0/0x1d70 net/batman-adv/network-coding.c:718 process_one_work+0x1688/0x2140 kernel/workqueue.c:2269 worker_thread+0x10bc/0x2730 kernel/workqueue.c:2415 kthread+0x551/0x590 kernel/kthread.c:293 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:143 [inline] kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:126 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:80 slab_alloc_node mm/slub.c:2907 [inline] slab_alloc mm/slub.c:2916 [inline] __kmalloc+0x2bb/0x4b0 mm/slub.c:3982 kmalloc_array+0x90/0x140 include/linux/slab.h:594 batadv_hash_new+0x129/0x530 net/batman-adv/hash.c:52 batadv_originator_init+0x9b/0x370 net/batman-adv/originator.c:211 batadv_mesh_init+0x4dc/0x9d0 net/batman-adv/main.c:204 batadv_softif_init_late+0x6d8/0xa30 net/batman-adv/soft-interface.c:857 register_netdevice+0xbbc/0x37d0 net/core/dev.c:9760 __rtnl_newlink net/core/rtnetlink.c:3454 [inline] rtnl_newlink+0x2e77/0x3ed0 net/core/rtnetlink.c:3500 rtnetlink_rcv_msg+0x142b/0x18c0 net/core/rtnetlink.c:5563 netlink_rcv_skb+0x6d7/0x7e0 net/netlink/af_netlink.c:2470 rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:5581 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x11c8/0x1490 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x173a/0x1840 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg net/socket.c:671 [inline] __sys_sendto+0x9dc/0xc80 net/socket.c:1992 __do_sys_sendto net/socket.c:2004 [inline] __se_sys_sendto+0x107/0x130 net/socket.c:2000 __x64_sys_sendto+0x6e/0x90 net/socket.c:2000 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48 entry_SYSCALL_64_after_hwframe+0x44/0xa9 =====================================================
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