Hello, syzbot found the following crash on:
HEAD commit: 21c44613 kmsan: page_alloc: more assuring comment git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=1533f00c100000 kernel config: https://syzkaller.appspot.com/x/.config?x=a5915107b3106aaa dashboard link: https://syzkaller.appspot.com/bug?extid=a83a64bf2be17a4479cf compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) 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+a83a64bf2be17a447...@syzkaller.appspotmail.com ===================================================== BUG: KMSAN: uninit-value in pskb_may_pull include/linux/skbuff.h:2333 [inline] BUG: KMSAN: uninit-value in skb_gro_header_slow include/linux/netdevice.h:2768 [inline] BUG: KMSAN: uninit-value in inet_gro_receive+0x451/0x1a10 net/ipv4/af_inet.c:1423 CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.6.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x220 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215 pskb_may_pull include/linux/skbuff.h:2333 [inline] skb_gro_header_slow include/linux/netdevice.h:2768 [inline] inet_gro_receive+0x451/0x1a10 net/ipv4/af_inet.c:1423 dev_gro_receive+0x2799/0x3260 net/core/dev.c:5774 napi_gro_receive+0x619/0xf90 net/core/dev.c:5908 gro_cell_poll+0x24c/0x400 net/core/gro_cells.c:60 napi_poll net/core/dev.c:6571 [inline] net_rx_action+0x786/0x1aa0 net/core/dev.c:6639 __do_softirq+0x311/0x83d kernel/softirq.c:293 run_ksoftirqd+0x25/0x40 kernel/softirq.c:607 smpboot_thread_fn+0x493/0x980 kernel/smpboot.c:165 kthread+0x4b5/0x4f0 kernel/kthread.c:256 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:353 Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310 __msan_chain_origin+0x50/0x90 mm/kmsan/kmsan_instr.c:165 __skb_pull include/linux/skbuff.h:2305 [inline] skb_pull_inline include/linux/skbuff.h:2312 [inline] eth_type_trans+0x684/0xa90 net/ethernet/eth.c:165 ip_tunnel_rcv+0xe8b/0x1ae0 net/ipv4/ip_tunnel.c:416 erspan_rcv net/ipv4/ip_gre.c:321 [inline] gre_rcv+0x155e/0x1940 net/ipv4/ip_gre.c:419 gre_rcv+0x2dd/0x3c0 net/ipv4/gre_demux.c:163 ip_protocol_deliver_rcu+0x700/0xbc0 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_local_deliver+0x62a/0x7c0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:442 [inline] ip_rcv_finish net/ipv4/ip_input.c:428 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_rcv+0x6cf/0x750 net/ipv4/ip_input.c:538 __netif_receive_skb_one_core net/core/dev.c:5187 [inline] __netif_receive_skb net/core/dev.c:5301 [inline] process_backlog+0xf0b/0x1410 net/core/dev.c:6133 napi_poll net/core/dev.c:6571 [inline] net_rx_action+0x786/0x1aa0 net/core/dev.c:6639 __do_softirq+0x311/0x83d kernel/softirq.c:293 Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310 __msan_chain_origin+0x50/0x90 mm/kmsan/kmsan_instr.c:165 __skb_pull include/linux/skbuff.h:2305 [inline] skb_pull_rcsum+0x2ca/0x4f0 net/core/skbuff.c:3621 __iptunnel_pull_header+0x14b/0xbd0 net/ipv4/ip_tunnel_core.c:97 erspan_rcv net/ipv4/ip_gre.c:279 [inline] gre_rcv+0x6d8/0x1940 net/ipv4/ip_gre.c:419 gre_rcv+0x2dd/0x3c0 net/ipv4/gre_demux.c:163 ip_protocol_deliver_rcu+0x700/0xbc0 net/ipv4/ip_input.c:204 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_local_deliver+0x62a/0x7c0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:442 [inline] ip_rcv_finish net/ipv4/ip_input.c:428 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip_rcv+0x6cf/0x750 net/ipv4/ip_input.c:538 __netif_receive_skb_one_core net/core/dev.c:5187 [inline] __netif_receive_skb net/core/dev.c:5301 [inline] process_backlog+0xf0b/0x1410 net/core/dev.c:6133 napi_poll net/core/dev.c:6571 [inline] net_rx_action+0x786/0x1aa0 net/core/dev.c:6639 __do_softirq+0x311/0x83d kernel/softirq.c:293 Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310 kmsan_memcpy_memmove_metadata+0x272/0x2e0 mm/kmsan/kmsan.c:247 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:267 __msan_memcpy+0x43/0x50 mm/kmsan/kmsan_instr.c:116 pskb_expand_head+0x38b/0x1b00 net/core/skbuff.c:1636 __skb_cow include/linux/skbuff.h:3169 [inline] skb_cow_head include/linux/skbuff.h:3203 [inline] ip_tunnel_xmit+0x2a10/0x34f0 net/ipv4/ip_tunnel.c:811 __gre_xmit net/ipv4/ip_gre.c:448 [inline] erspan_xmit+0x1779/0x2ae0 net/ipv4/ip_gre.c:683 __netdev_start_xmit include/linux/netdevice.h:4523 [inline] netdev_start_xmit include/linux/netdevice.h:4537 [inline] xmit_one net/core/dev.c:3477 [inline] dev_hard_start_xmit+0x531/0xab0 net/core/dev.c:3493 sch_direct_xmit+0x512/0x18b0 net/sched/sch_generic.c:314 qdisc_restart net/sched/sch_generic.c:377 [inline] __qdisc_run+0x15ec/0x3350 net/sched/sch_generic.c:385 qdisc_run include/net/pkt_sched.h:126 [inline] __dev_xmit_skb net/core/dev.c:3668 [inline] __dev_queue_xmit+0x23b7/0x3b20 net/core/dev.c:4021 dev_queue_xmit+0x4b/0x60 net/core/dev.c:4085 neigh_resolve_output+0xab0/0xb40 net/core/neighbour.c:1487 neigh_output include/net/neighbour.h:510 [inline] ip_finish_output2+0x1acc/0x2610 net/ipv4/ip_output.c:228 __ip_finish_output+0xaa7/0xd80 net/ipv4/ip_output.c:306 ip_finish_output+0x166/0x410 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_mc_output+0xfbf/0x1090 net/ipv4/ip_output.c:415 dst_output include/net/dst.h:436 [inline] ip_local_out net/ipv4/ip_output.c:125 [inline] ip_send_skb+0x179/0x360 net/ipv4/ip_output.c:1560 udp_send_skb+0x1046/0x18b0 net/ipv4/udp.c:891 udp_sendmsg+0x3bb5/0x4100 net/ipv4/udp.c:1178 inet_sendmsg+0x276/0x2e0 net/ipv4/af_inet.c:807 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg net/socket.c:672 [inline] ____sys_sendmsg+0x1056/0x1350 net/socket.c:2345 ___sys_sendmsg net/socket.c:2399 [inline] __sys_sendmmsg+0x5b6/0xc90 net/socket.c:2489 __do_sys_sendmmsg net/socket.c:2518 [inline] __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2515 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2515 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:80 slab_alloc_node mm/slub.c:2801 [inline] __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4420 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1081 [inline] alloc_skb_with_frags+0x18c/0xa70 net/core/skbuff.c:5764 sock_alloc_send_pskb+0xada/0xc60 net/core/sock.c:2245 sock_alloc_send_skb+0xca/0xe0 net/core/sock.c:2262 __ip_append_data+0x3b41/0x5660 net/ipv4/ip_output.c:1089 ip_make_skb+0x394/0x880 net/ipv4/ip_output.c:1626 udp_sendmsg+0x36dc/0x4100 net/ipv4/udp.c:1173 inet_sendmsg+0x276/0x2e0 net/ipv4/af_inet.c:807 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg net/socket.c:672 [inline] ____sys_sendmsg+0x1056/0x1350 net/socket.c:2345 ___sys_sendmsg net/socket.c:2399 [inline] __sys_sendmmsg+0x5b6/0xc90 net/socket.c:2489 __do_sys_sendmmsg net/socket.c:2518 [inline] __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2515 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2515 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9 ===================================================== --- This bug is generated by a bot. 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