===================================================== BUG: KMSAN: uninit-value in pskb_may_pull include/linux/skbuff.h:2303 [inline] BUG: KMSAN: uninit-value in __iptunnel_pull_header+0x30c/0xbd0 net/ipv4/ip_tunnel_core.c:94 CPU: 1 PID: 1401 Comm: syz-executor.3 Not tainted 5.6.0-rc2-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:2303 [inline] __iptunnel_pull_header+0x30c/0xbd0 net/ipv4/ip_tunnel_core.c:94 iptunnel_pull_header include/net/ip_tunnels.h:411 [inline] gre_rcv+0x15e/0x19c0 net/ipv6/ip6_gre.c:606 ip6_protocol_deliver_rcu+0x181b/0x22c0 net/ipv6/ip6_input.c:432 ip6_input_finish net/ipv6/ip6_input.c:473 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ip6_input net/ipv6/ip6_input.c:482 [inline] ip6_mc_input+0xdf2/0x1460 net/ipv6/ip6_input.c:576 dst_input include/net/dst.h:442 [inline] ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ipv6_rcv+0x683/0x710 net/ipv6/ip6_input.c:306 __netif_receive_skb_one_core net/core/dev.c:5198 [inline] __netif_receive_skb net/core/dev.c:5312 [inline] netif_receive_skb_internal net/core/dev.c:5402 [inline] netif_receive_skb+0x66b/0xf20 net/core/dev.c:5461 tun_rx_batched include/linux/skbuff.h:4321 [inline] tun_get_user+0x6aef/0x6f60 drivers/net/tun.c:1997 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2026 call_write_iter include/linux/fs.h:1901 [inline] new_sync_write fs/read_write.c:483 [inline] __vfs_write+0xa5a/0xca0 fs/read_write.c:496 vfs_write+0x44a/0x8f0 fs/read_write.c:558 ksys_write+0x267/0x450 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write+0x92/0xb0 fs/read_write.c:620 __x64_sys_write+0x4a/0x70 fs/read_write.c:620 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c849 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f118c596c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f118c5976d4 RCX: 000000000045c849 RDX: 0000000000000fca RSI: 0000000020000180 RDI: 0000000000000003 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000d0e R14: 00000000004cf3a8 R15: 000000000076bf0c 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:82 slab_alloc_node mm/slub.c:2793 [inline] __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4401 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1051 [inline] alloc_skb_with_frags+0x18c/0xa70 net/core/skbuff.c:5766 sock_alloc_send_pskb+0xada/0xc60 net/core/sock.c:2242 tun_alloc_skb drivers/net/tun.c:1529 [inline] tun_get_user+0x10ae/0x6f60 drivers/net/tun.c:1843 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2026 call_write_iter include/linux/fs.h:1901 [inline] new_sync_write fs/read_write.c:483 [inline] __vfs_write+0xa5a/0xca0 fs/read_write.c:496 vfs_write+0x44a/0x8f0 fs/read_write.c:558 ksys_write+0x267/0x450 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write+0x92/0xb0 fs/read_write.c:620 __x64_sys_write+0x4a/0x70 fs/read_write.c:620 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x44/0xa9 =====================================================