Hello, syzbot found the following issue on: HEAD commit: 4ebaab5f kmsan: drop unneeded references to kmsan_context_.. git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=17ac508ed00000 kernel config: https://syzkaller.appspot.com/x/.config?x=ab8076fe8508c0d3 dashboard link: https://syzkaller.appspot.com/bug?extid=106457891e3cf3b273a9 compiler: Debian clang version 11.0.1-2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=138f4972d00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1624ffced00000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+106457891e3cf3b273a9@xxxxxxxxxxxxxxxxxxxxxxxxx ===================================================== BUG: KMSAN: uninit-value in virtio_net_hdr_to_skb+0x1414/0x14f0 include/linux/virtio_net.h:86 CPU: 0 PID: 8426 Comm: syz-executor777 Not tainted 5.12.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x24c/0x2e0 lib/dump_stack.c:120 kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118 __msan_warning+0x5c/0xa0 mm/kmsan/kmsan_instr.c:197 virtio_net_hdr_to_skb+0x1414/0x14f0 include/linux/virtio_net.h:86 packet_snd net/packet/af_packet.c:2994 [inline] packet_sendmsg+0x85b8/0x99d0 net/packet/af_packet.c:3031 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg net/socket.c:674 [inline] kernel_sendmsg+0x22c/0x2f0 net/socket.c:694 sock_no_sendpage+0x205/0x2b0 net/core/sock.c:2860 kernel_sendpage+0x47a/0x590 net/socket.c:3631 sock_sendpage+0x161/0x1a0 net/socket.c:947 pipe_to_sendpage+0x3e4/0x520 fs/splice.c:364 splice_from_pipe_feed fs/splice.c:418 [inline] __splice_from_pipe+0x5e3/0xff0 fs/splice.c:562 splice_from_pipe fs/splice.c:597 [inline] generic_splice_sendpage+0x1d5/0x2c0 fs/splice.c:746 do_splice_from fs/splice.c:767 [inline] do_splice+0x23c3/0x2c10 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x8fa/0xb50 fs/splice.c:1332 __x64_sys_splice+0x6e/0x90 fs/splice.c:1332 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x449a39 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8ed790b2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00000000004cf518 RCX: 0000000000449a39 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00000000004cf510 R08: 000000000004ffe0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cf51c R13: 000000000049e46c R14: 6d32cc5e8ead0600 R15: 0000000000022000 Uninit was created at: kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:121 kmsan_alloc_page+0xd0/0x1e0 mm/kmsan/kmsan_shadow.c:274 __alloc_pages_nodemask+0x827/0xf90 mm/page_alloc.c:5044 alloc_pages_current+0x7b6/0xb60 mm/mempolicy.c:2277 alloc_pages include/linux/gfp.h:561 [inline] alloc_slab_page mm/slub.c:1653 [inline] allocate_slab+0x364/0x1260 mm/slub.c:1793 new_slab mm/slub.c:1856 [inline] new_slab_objects mm/slub.c:2602 [inline] ___slab_alloc+0xd42/0x1930 mm/slub.c:2765 __slab_alloc mm/slub.c:2805 [inline] slab_alloc_node mm/slub.c:2886 [inline] slab_alloc mm/slub.c:2931 [inline] kmem_cache_alloc_trace+0xc53/0x1030 mm/slub.c:2948 kmalloc include/linux/slab.h:554 [inline] kzalloc include/linux/slab.h:684 [inline] ____ip_mc_inc_group+0x4d7/0x10b0 net/ipv4/igmp.c:1435 __ip_mc_inc_group net/ipv4/igmp.c:1470 [inline] ip_mc_inc_group net/ipv4/igmp.c:1476 [inline] ip_mc_up+0x1ec/0x410 net/ipv4/igmp.c:1775 inetdev_event+0x2036/0x20e0 net/ipv4/devinet.c:1573 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x123/0x290 kernel/notifier.c:410 __dev_notify_flags+0x5ac/0xba0 net/core/dev.c:2075 dev_change_flags+0x1f8/0x280 net/core/dev.c:8762 do_setlink+0x17f6/0x7890 net/core/rtnetlink.c:2708 __rtnl_newlink net/core/rtnetlink.c:3376 [inline] rtnl_newlink+0x2fc4/0x3d80 net/core/rtnetlink.c:3491 rtnetlink_rcv_msg+0x143b/0x18e0 net/core/rtnetlink.c:5553 netlink_rcv_skb+0x6fa/0x810 net/netlink/af_netlink.c:2502 rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:5571 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x11d6/0x14a0 net/netlink/af_netlink.c:1338 netlink_sendmsg+0x1740/0x1840 net/netlink/af_netlink.c:1927 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg net/socket.c:674 [inline] __sys_sendto+0x9ea/0xc60 net/socket.c:1977 __do_sys_sendto net/socket.c:1989 [inline] __se_sys_sendto+0x107/0x130 net/socket.c:1985 __x64_sys_sendto+0x6e/0x90 net/socket.c:1985 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48 entry_SYSCALL_64_after_hwframe+0x44/0xae ===================================================== --- This report is generated by a bot. 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