Re: KMSAN: uninit-value in __netif_receive_skb_core
On Fri, Apr 13, 2018 at 10:20 AM, Toshiaki Makita wrote: > On 2018/04/12 17:03, Dmitry Vyukov wrote: >> On Thu, Apr 12, 2018 at 10:01 AM, syzbot >> wrote: >>> Hello, >>> >>> syzbot hit the following crash on https://github.com/google/kmsan.git/master >>> commit >>> e2ab7e8abba47a2f2698216258e5d8727ae58717 (Fri Apr 6 16:24:31 2018 +) >>> kmsan: temporarily disable visitAsmInstruction() to help syzbot >>> syzbot dashboard link: >>> https://syzkaller.appspot.com/bug?extid=b202b7208664142954fa >>> >>> Unfortunately, I don't have any reproducer for this crash yet. >>> Raw console output: >>> https://syzkaller.appspot.com/x/log.txt?id=535651643762 >>> Kernel config: >>> https://syzkaller.appspot.com/x/.config?id=6627248707860932248 >>> compiler: clang version 7.0.0 (trunk 329391) >> >> +Toshiaki as this seems to be related to the recent vlan tagging changes. > > seems not... > "Uninit was stored to memory at:" shows uninitialized memory was stored > before where I modified the code (skb_reorder_vlan_header). > > I'm not sure what this uninit memory means. > To me it looks like the memory is initialized by user provided data. > > (iov in packet sock -> skb->data -> skb->protocol) > > The reproducer provides 4 bytes after ethernet header, so it should be > sufficient for a vlan tag. This will set skb->len to 4 and fill the > 4-byte contents in packet_snd(). skb_vlan_untag() is reading the user > provided 4-byte skb->data. It is ensured that skb_vlan_untag() does not > read beyond skb->len since it calls pskb_may_pull(). At this point I am > failing to find what I am missing. Eric, You mentioned something about assumption that the __vlan_insert_inner_tag() helper would only be called from __netif_receive_skb_core(). Can you elaborate? >> This also seems to be related to >> https://groups.google.com/d/msg/syzkaller-bugs/VRH9NnUi2k0/90GYsAeRBgAJ >> >>> IMPORTANT: if you fix the bug, please add the following tag to the commit: >>> Reported-by: syzbot+b202b720866414295...@syzkaller.appspotmail.com >>> It will help syzbot understand when the bug is fixed. See footer for >>> details. >>> If you forward the report, please keep this part and the footer. >>> >>> == >>> BUG: KMSAN: uninit-value in __read_once_size include/linux/compiler.h:197 >>> [inline] >>> BUG: KMSAN: uninit-value in deliver_ptype_list_skb net/core/dev.c:1908 >>> [inline] >>> BUG: KMSAN: uninit-value in __netif_receive_skb_core+0x4630/0x4a80 >>> net/core/dev.c:4545 >>> CPU: 0 PID: 5999 Comm: syz-executor3 Not tainted 4.16.0+ #82 >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >>> Google 01/01/2011 >>> Call Trace: >>> >>> __dump_stack lib/dump_stack.c:17 [inline] >>> dump_stack+0x185/0x1d0 lib/dump_stack.c:53 >>> kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 >>> __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676 >>> __read_once_size include/linux/compiler.h:197 [inline] >>> deliver_ptype_list_skb net/core/dev.c:1908 [inline] >>> __netif_receive_skb_core+0x4630/0x4a80 net/core/dev.c:4545 >>> __netif_receive_skb net/core/dev.c:4627 [inline] >>> process_backlog+0x62d/0xe20 net/core/dev.c:5307 >>> napi_poll net/core/dev.c:5705 [inline] >>> net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771 >>> __do_softirq+0x56d/0x93d kernel/softirq.c:285 >>> do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1040 >>> >>> do_softirq kernel/softirq.c:329 [inline] >>> __local_bh_enable_ip+0x114/0x140 kernel/softirq.c:182 >>> local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32 >>> rcu_read_unlock_bh include/linux/rcupdate.h:726 [inline] >>> __dev_queue_xmit+0x2a31/0x2b60 net/core/dev.c:3584 >>> dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590 >>> packet_snd net/packet/af_packet.c:2944 [inline] >>> packet_sendmsg+0x7c57/0x8a10 net/packet/af_packet.c:2969 >>> sock_sendmsg_nosec net/socket.c:630 [inline] >>> sock_sendmsg net/socket.c:640 [inline] >>> sock_write_iter+0x3b9/0x470 net/socket.c:909 >>> do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776 >>> do_iter_write+0x30d/0xd40 fs/read_write.c:932 >>> vfs_writev fs/read_write.c:977 [inline] >>> do_writev+0x3c9/0x830 fs/read_write.c:1012 >>> SYSC_writev+0x9b/0xb0 fs/read_write.c:1085 >>> SyS_writev+0x56/0x80 fs/read_write.c:1082 >>> do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 >>> entry_SYSCALL_64_after_hwframe+0x3d/0xa2 >>> RIP: 0033:0x455259 >>> RSP: 002b:7fb53ede8c68 EFLAGS: 0246 ORIG_RAX: 0014 >>> RAX: ffda RBX: 7fb53ede96d4 RCX: 00455259 >>> RDX: 0001 RSI: 200010c0 RDI: 0013 >>> RBP: 0072bea0 R08: R09: >>> R10: R11: 0246 R12: >>> R13: 06cd R14: 006fd3d8 R15: >>> >>> Uninit was stored to memory at: >>> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] >>> kmsa
Re: KMSAN: uninit-value in __netif_receive_skb_core
On 2018/04/12 17:03, Dmitry Vyukov wrote: > On Thu, Apr 12, 2018 at 10:01 AM, syzbot > wrote: >> Hello, >> >> syzbot hit the following crash on https://github.com/google/kmsan.git/master >> commit >> e2ab7e8abba47a2f2698216258e5d8727ae58717 (Fri Apr 6 16:24:31 2018 +) >> kmsan: temporarily disable visitAsmInstruction() to help syzbot >> syzbot dashboard link: >> https://syzkaller.appspot.com/bug?extid=b202b7208664142954fa >> >> Unfortunately, I don't have any reproducer for this crash yet. >> Raw console output: >> https://syzkaller.appspot.com/x/log.txt?id=535651643762 >> Kernel config: >> https://syzkaller.appspot.com/x/.config?id=6627248707860932248 >> compiler: clang version 7.0.0 (trunk 329391) > > +Toshiaki as this seems to be related to the recent vlan tagging changes. seems not... "Uninit was stored to memory at:" shows uninitialized memory was stored before where I modified the code (skb_reorder_vlan_header). I'm not sure what this uninit memory means. To me it looks like the memory is initialized by user provided data. (iov in packet sock -> skb->data -> skb->protocol) The reproducer provides 4 bytes after ethernet header, so it should be sufficient for a vlan tag. This will set skb->len to 4 and fill the 4-byte contents in packet_snd(). skb_vlan_untag() is reading the user provided 4-byte skb->data. It is ensured that skb_vlan_untag() does not read beyond skb->len since it calls pskb_may_pull(). At this point I am failing to find what I am missing. > This also seems to be related to > https://groups.google.com/d/msg/syzkaller-bugs/VRH9NnUi2k0/90GYsAeRBgAJ > >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+b202b720866414295...@syzkaller.appspotmail.com >> It will help syzbot understand when the bug is fixed. See footer for >> details. >> If you forward the report, please keep this part and the footer. >> >> == >> BUG: KMSAN: uninit-value in __read_once_size include/linux/compiler.h:197 >> [inline] >> BUG: KMSAN: uninit-value in deliver_ptype_list_skb net/core/dev.c:1908 >> [inline] >> BUG: KMSAN: uninit-value in __netif_receive_skb_core+0x4630/0x4a80 >> net/core/dev.c:4545 >> CPU: 0 PID: 5999 Comm: syz-executor3 Not tainted 4.16.0+ #82 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >> Google 01/01/2011 >> Call Trace: >> >> __dump_stack lib/dump_stack.c:17 [inline] >> dump_stack+0x185/0x1d0 lib/dump_stack.c:53 >> kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 >> __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676 >> __read_once_size include/linux/compiler.h:197 [inline] >> deliver_ptype_list_skb net/core/dev.c:1908 [inline] >> __netif_receive_skb_core+0x4630/0x4a80 net/core/dev.c:4545 >> __netif_receive_skb net/core/dev.c:4627 [inline] >> process_backlog+0x62d/0xe20 net/core/dev.c:5307 >> napi_poll net/core/dev.c:5705 [inline] >> net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771 >> __do_softirq+0x56d/0x93d kernel/softirq.c:285 >> do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1040 >> >> do_softirq kernel/softirq.c:329 [inline] >> __local_bh_enable_ip+0x114/0x140 kernel/softirq.c:182 >> local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32 >> rcu_read_unlock_bh include/linux/rcupdate.h:726 [inline] >> __dev_queue_xmit+0x2a31/0x2b60 net/core/dev.c:3584 >> dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590 >> packet_snd net/packet/af_packet.c:2944 [inline] >> packet_sendmsg+0x7c57/0x8a10 net/packet/af_packet.c:2969 >> sock_sendmsg_nosec net/socket.c:630 [inline] >> sock_sendmsg net/socket.c:640 [inline] >> sock_write_iter+0x3b9/0x470 net/socket.c:909 >> do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776 >> do_iter_write+0x30d/0xd40 fs/read_write.c:932 >> vfs_writev fs/read_write.c:977 [inline] >> do_writev+0x3c9/0x830 fs/read_write.c:1012 >> SYSC_writev+0x9b/0xb0 fs/read_write.c:1085 >> SyS_writev+0x56/0x80 fs/read_write.c:1082 >> do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 >> entry_SYSCALL_64_after_hwframe+0x3d/0xa2 >> RIP: 0033:0x455259 >> RSP: 002b:7fb53ede8c68 EFLAGS: 0246 ORIG_RAX: 0014 >> RAX: ffda RBX: 7fb53ede96d4 RCX: 00455259 >> RDX: 0001 RSI: 200010c0 RDI: 0013 >> RBP: 0072bea0 R08: R09: >> R10: R11: 0246 R12: >> R13: 06cd R14: 006fd3d8 R15: >> >> Uninit was stored to memory at: >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] >> kmsan_save_stack mm/kmsan/kmsan.c:293 [inline] >> kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684 >> __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:521 >> skb_vlan_untag+0x950/0xee0 include/linux/if_vlan.h:597 >> __netif_receive_skb_core+0x70a/0x4a80 net/core/dev.c:4460 >> __netif_receive_skb net/core/dev.c:4627 [i
Re: KMSAN: uninit-value in __netif_receive_skb_core
syzbot has found reproducer for the following crash on https://github.com/google/kmsan.git/master commit 35ff515e4bda2646f6c881d33951c306ea9c282a (Tue Apr 10 08:59:43 2018 +) Merge pull request #11 from parkerduckworth/readme syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=b202b7208664142954fa So far this crash happened 3 times on https://github.com/google/kmsan.git/master. C reproducer: https://syzkaller.appspot.com/x/repro.c?id=455991623680 syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=4590273065648128 Raw console output: https://syzkaller.appspot.com/x/log.txt?id=4631921027973120 Kernel config: https://syzkaller.appspot.com/x/.config?id=6627248707860932248 compiler: clang version 7.0.0 (trunk 329391) IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+b202b720866414295...@syzkaller.appspotmail.com It will help syzbot understand when the bug is fixed. == BUG: KMSAN: uninit-value in __read_once_size include/linux/compiler.h:197 [inline] BUG: KMSAN: uninit-value in deliver_ptype_list_skb net/core/dev.c:1908 [inline] BUG: KMSAN: uninit-value in __netif_receive_skb_core+0x4630/0x4a80 net/core/dev.c:4545 CPU: 0 PID: 3514 Comm: syzkaller031167 Not tainted 4.16.0+ #83 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x185/0x1d0 lib/dump_stack.c:53 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676 __read_once_size include/linux/compiler.h:197 [inline] deliver_ptype_list_skb net/core/dev.c:1908 [inline] __netif_receive_skb_core+0x4630/0x4a80 net/core/dev.c:4545 __netif_receive_skb net/core/dev.c:4627 [inline] process_backlog+0x62d/0xe20 net/core/dev.c:5307 napi_poll net/core/dev.c:5705 [inline] net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771 __do_softirq+0x56d/0x93d kernel/softirq.c:285 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1040 do_softirq kernel/softirq.c:329 [inline] __local_bh_enable_ip+0x114/0x140 kernel/softirq.c:182 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32 rcu_read_unlock_bh include/linux/rcupdate.h:726 [inline] __dev_queue_xmit+0x2a31/0x2b60 net/core/dev.c:3584 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590 packet_snd net/packet/af_packet.c:2944 [inline] packet_sendmsg+0x7c57/0x8a10 net/packet/af_packet.c:2969 sock_sendmsg_nosec net/socket.c:630 [inline] sock_sendmsg net/socket.c:640 [inline] sock_write_iter+0x3b9/0x470 net/socket.c:909 do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776 do_iter_write+0x30d/0xd40 fs/read_write.c:932 vfs_writev fs/read_write.c:977 [inline] do_writev+0x3c9/0x830 fs/read_write.c:1012 SYSC_writev+0x9b/0xb0 fs/read_write.c:1085 SyS_writev+0x56/0x80 fs/read_write.c:1082 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x43ffb9 RSP: 002b:7ffd42187708 EFLAGS: 0217 ORIG_RAX: 0014 RAX: ffda RBX: 004002c8 RCX: 0043ffb9 RDX: 0001 RSI: 200010c0 RDI: 0003 RBP: 006ca018 R08: 004002c8 R09: 004002c8 R10: 004002c8 R11: 0217 R12: 004018e0 R13: 00401970 R14: R15: Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] kmsan_save_stack mm/kmsan/kmsan.c:293 [inline] kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:521 skb_vlan_untag+0x950/0xee0 include/linux/if_vlan.h:597 __netif_receive_skb_core+0x70a/0x4a80 net/core/dev.c:4460 __netif_receive_skb net/core/dev.c:4627 [inline] process_backlog+0x62d/0xe20 net/core/dev.c:5307 napi_poll net/core/dev.c:5705 [inline] net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771 __do_softirq+0x56d/0x93d kernel/softirq.c:285 Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314 kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc_node mm/slub.c:2737 [inline] __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369 __kmalloc_reserve net/core/skbuff.c:138 [inline] __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206 alloc_skb include/linux/skbuff.h:984 [inline] alloc_skb_with_frags+0x1d4/0xb20 net/core/skbuff.c:5234 sock_alloc_send_pskb+0xb56/0x1190 net/core/sock.c:2085 packet_alloc_skb net/packet/af_packet.c:2803 [inline] packet_snd net/packet/af_packet.c:2894 [inline] packet_sendmsg+0x6444/0x8a10 net/packet/af_packet.c:2969 sock_sendmsg_nosec net/socket.c:630 [inline] sock_sendmsg net/socket.c:640 [inline] sock_write_iter+0x3b9/0x470 net/
Re: KMSAN: uninit-value in __netif_receive_skb_core
On Thu, Apr 12, 2018 at 10:01 AM, syzbot wrote: > Hello, > > syzbot hit the following crash on https://github.com/google/kmsan.git/master > commit > e2ab7e8abba47a2f2698216258e5d8727ae58717 (Fri Apr 6 16:24:31 2018 +) > kmsan: temporarily disable visitAsmInstruction() to help syzbot > syzbot dashboard link: > https://syzkaller.appspot.com/bug?extid=b202b7208664142954fa > > Unfortunately, I don't have any reproducer for this crash yet. > Raw console output: > https://syzkaller.appspot.com/x/log.txt?id=535651643762 > Kernel config: > https://syzkaller.appspot.com/x/.config?id=6627248707860932248 > compiler: clang version 7.0.0 (trunk 329391) +Toshiaki as this seems to be related to the recent vlan tagging changes. This also seems to be related to https://groups.google.com/d/msg/syzkaller-bugs/VRH9NnUi2k0/90GYsAeRBgAJ > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+b202b720866414295...@syzkaller.appspotmail.com > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > == > BUG: KMSAN: uninit-value in __read_once_size include/linux/compiler.h:197 > [inline] > BUG: KMSAN: uninit-value in deliver_ptype_list_skb net/core/dev.c:1908 > [inline] > BUG: KMSAN: uninit-value in __netif_receive_skb_core+0x4630/0x4a80 > net/core/dev.c:4545 > CPU: 0 PID: 5999 Comm: syz-executor3 Not tainted 4.16.0+ #82 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x185/0x1d0 lib/dump_stack.c:53 > kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 > __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676 > __read_once_size include/linux/compiler.h:197 [inline] > deliver_ptype_list_skb net/core/dev.c:1908 [inline] > __netif_receive_skb_core+0x4630/0x4a80 net/core/dev.c:4545 > __netif_receive_skb net/core/dev.c:4627 [inline] > process_backlog+0x62d/0xe20 net/core/dev.c:5307 > napi_poll net/core/dev.c:5705 [inline] > net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771 > __do_softirq+0x56d/0x93d kernel/softirq.c:285 > do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1040 > > do_softirq kernel/softirq.c:329 [inline] > __local_bh_enable_ip+0x114/0x140 kernel/softirq.c:182 > local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32 > rcu_read_unlock_bh include/linux/rcupdate.h:726 [inline] > __dev_queue_xmit+0x2a31/0x2b60 net/core/dev.c:3584 > dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590 > packet_snd net/packet/af_packet.c:2944 [inline] > packet_sendmsg+0x7c57/0x8a10 net/packet/af_packet.c:2969 > sock_sendmsg_nosec net/socket.c:630 [inline] > sock_sendmsg net/socket.c:640 [inline] > sock_write_iter+0x3b9/0x470 net/socket.c:909 > do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776 > do_iter_write+0x30d/0xd40 fs/read_write.c:932 > vfs_writev fs/read_write.c:977 [inline] > do_writev+0x3c9/0x830 fs/read_write.c:1012 > SYSC_writev+0x9b/0xb0 fs/read_write.c:1085 > SyS_writev+0x56/0x80 fs/read_write.c:1082 > do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x3d/0xa2 > RIP: 0033:0x455259 > RSP: 002b:7fb53ede8c68 EFLAGS: 0246 ORIG_RAX: 0014 > RAX: ffda RBX: 7fb53ede96d4 RCX: 00455259 > RDX: 0001 RSI: 200010c0 RDI: 0013 > RBP: 0072bea0 R08: R09: > R10: R11: 0246 R12: > R13: 06cd R14: 006fd3d8 R15: > > Uninit was stored to memory at: > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] > kmsan_save_stack mm/kmsan/kmsan.c:293 [inline] > kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684 > __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:521 > skb_vlan_untag+0x950/0xee0 include/linux/if_vlan.h:597 > __netif_receive_skb_core+0x70a/0x4a80 net/core/dev.c:4460 > __netif_receive_skb net/core/dev.c:4627 [inline] > process_backlog+0x62d/0xe20 net/core/dev.c:5307 > napi_poll net/core/dev.c:5705 [inline] > net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771 > __do_softirq+0x56d/0x93d kernel/softirq.c:285 > Uninit was created at: > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] > kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188 > kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314 > kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321 > slab_post_alloc_hook mm/slab.h:445 [inline] > slab_alloc_node mm/slub.c:2737 [inline] > __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369 > __kmalloc_reserve net/core/skbuff.c:138 [inline] > __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206 > alloc_skb include/linux/skbuff.h:984 [inline] > alloc_skb_with_frags+0x1d4/0xb20 net/core/skbuff.c:5234 > sock_alloc_send_pskb+0xb56/0x1