syzbot has found a reproducer for the following issue on: HEAD commit: 73d62e81 kmsan: random: prevent boot-time reports in _mix_.. git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=13bd4607500000 kernel config: https://syzkaller.appspot.com/x/.config?x=eef728deea880383 dashboard link: https://syzkaller.appspot.com/bug?extid=b024befb3ca7990fea37 compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126c8379500000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17cdf7b5500000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b024befb3ca7990fea37@xxxxxxxxxxxxxxxxxxxxxxxxx ===================================================== BUG: KMSAN: uninit-value in __skb_checksum_complete+0x421/0x630 net/core/skbuff.c:2846 CPU: 0 PID: 497 Comm: kworker/u4:11 Not tainted 5.10.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: <IRQ> __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:118 __msan_warning+0x5f/0xa0 mm/kmsan/kmsan_instr.c:197 __skb_checksum_complete+0x421/0x630 net/core/skbuff.c:2846 __skb_checksum_validate_complete include/linux/skbuff.h:4014 [inline] icmp_rcv+0x94b/0x1d70 net/ipv4/icmp.c:1081 ip_protocol_deliver_rcu+0x572/0xc50 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_local_deliver+0x583/0x8d0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:449 [inline] ip_rcv_finish net/ipv4/ip_input.c:428 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_rcv+0x5c3/0x840 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core net/core/dev.c:5315 [inline] __netif_receive_skb+0x1ec/0x640 net/core/dev.c:5429 process_backlog+0x523/0xc10 net/core/dev.c:6319 napi_poll+0x420/0x1010 net/core/dev.c:6763 net_rx_action+0x35c/0xd40 net/core/dev.c:6833 __do_softirq+0x1a9/0x6fa kernel/softirq.c:298 asm_call_irq_on_stack+0xf/0x20 </IRQ> __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0x6e/0x90 arch/x86/kernel/irq_64.c:77 do_softirq kernel/softirq.c:343 [inline] __local_bh_enable_ip+0x184/0x1d0 kernel/softirq.c:195 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32 rcu_read_unlock_bh include/linux/rcupdate.h:730 [inline] __dev_queue_xmit+0x3a9b/0x4520 net/core/dev.c:4167 dev_queue_xmit+0x4b/0x60 net/core/dev.c:4173 batadv_send_skb_packet+0x622/0x970 net/batman-adv/send.c:108 batadv_send_broadcast_skb+0x76/0x90 net/batman-adv/send.c:127 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:394 [inline] batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0xb3a/0xf00 net/batman-adv/bat_iv_ogm.c:1712 process_one_work+0x121c/0x1fc0 kernel/workqueue.c:2272 worker_thread+0x10cc/0x2740 kernel/workqueue.c:2418 kthread+0x51c/0x560 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:121 [inline] kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:289 kmsan_memcpy_memmove_metadata+0x25e/0x2d0 mm/kmsan/kmsan.c:226 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:246 __msan_memcpy+0x46/0x60 mm/kmsan/kmsan_instr.c:110 csum_partial_copy_nocheck include/net/checksum.h:51 [inline] skb_copy_and_csum_bits+0x23e/0x13e0 net/core/skbuff.c:2733 icmp_glue_bits+0x155/0x400 net/ipv4/icmp.c:356 __ip_append_data+0x4f8e/0x6210 net/ipv4/ip_output.c:1139 ip_append_data+0x326/0x490 net/ipv4/ip_output.c:1323 icmp_push_reply+0x1f8/0x810 net/ipv4/icmp.c:374 __icmp_send+0x2a98/0x3a90 net/ipv4/icmp.c:762 icmp_send include/net/icmp.h:43 [inline] __udp4_lib_rcv+0x421f/0x5880 net/ipv4/udp.c:2405 udp_rcv+0x5c/0x70 net/ipv4/udp.c:2564 ip_protocol_deliver_rcu+0x572/0xc50 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_local_deliver+0x583/0x8d0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:449 [inline] ip_rcv_finish net/ipv4/ip_input.c:428 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_rcv+0x5c3/0x840 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core net/core/dev.c:5315 [inline] __netif_receive_skb+0x1ec/0x640 net/core/dev.c:5429 process_backlog+0x523/0xc10 net/core/dev.c:6319 napi_poll+0x420/0x1010 net/core/dev.c:6763 net_rx_action+0x35c/0xd40 net/core/dev.c:6833 __do_softirq+0x1a9/0x6fa kernel/softirq.c:298 Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:121 [inline] kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:289 kmsan_memcpy_memmove_metadata+0x25e/0x2d0 mm/kmsan/kmsan.c:226 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:246 __msan_memcpy+0x46/0x60 mm/kmsan/kmsan_instr.c:110 pskb_expand_head+0x3eb/0x1df0 net/core/skbuff.c:1631 __skb_cow include/linux/skbuff.h:3165 [inline] skb_cow_head include/linux/skbuff.h:3199 [inline] batadv_skb_head_push+0x2ce/0x410 net/batman-adv/soft-interface.c:75 batadv_send_skb_packet+0x1ed/0x970 net/batman-adv/send.c:86 batadv_send_broadcast_skb+0x76/0x90 net/batman-adv/send.c:127 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:394 [inline] batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0xb3a/0xf00 net/batman-adv/bat_iv_ogm.c:1712 process_one_work+0x121c/0x1fc0 kernel/workqueue.c:2272 worker_thread+0x10cc/0x2740 kernel/workqueue.c:2418 kthread+0x51c/0x560 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Uninit was created at: kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:121 kmsan_alloc_page+0xd3/0x1f0 mm/kmsan/kmsan_shadow.c:274 __alloc_pages_nodemask+0x84e/0xfb0 mm/page_alloc.c:4989 __alloc_pages include/linux/gfp.h:511 [inline] __alloc_pages_node include/linux/gfp.h:524 [inline] alloc_pages_node include/linux/gfp.h:538 [inline] __page_frag_cache_refill mm/page_alloc.c:5065 [inline] page_frag_alloc+0x35b/0x890 mm/page_alloc.c:5095 __napi_alloc_skb+0x1c0/0xab0 net/core/skbuff.c:519 napi_alloc_skb include/linux/skbuff.h:2870 [inline] page_to_skb+0x142/0x1640 drivers/net/virtio_net.c:389 receive_mergeable+0xee6/0x5be0 drivers/net/virtio_net.c:949 receive_buf+0x2db/0x2ba0 drivers/net/virtio_net.c:1059 virtnet_receive drivers/net/virtio_net.c:1351 [inline] virtnet_poll+0xa51/0x1d10 drivers/net/virtio_net.c:1456 napi_poll+0x420/0x1010 net/core/dev.c:6763 net_rx_action+0x35c/0xd40 net/core/dev.c:6833 __do_softirq+0x1a9/0x6fa kernel/softirq.c:298 =====================================================
