| Message ID | CANn89iLX+GPK6WWcz76T_z4_hMv4aNy8nREVqGKP-q+UqQNOxA@mail.gmail.com |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, Jan 9, 2017 at 6:21 PM, Eric Dumazet <edumazet@google.com> wrote: > On Mon, Jan 9, 2017 at 9:11 AM, Andrey Konovalov <andreyknvl@google.com> wrote: >> On Mon, Jan 9, 2017 at 6:08 PM, Andrey Konovalov <andreyknvl@google.com> wrote: >>> Hi! >>> >>> I've got the following error report while running the syzkaller fuzzer. >>> >>> On commit a121103c922847ba5010819a3f250f1f7fc84ab8 (4.10-rc3). >>> >>> A reproducer is attached. >>> >>> ================================================================== >>> BUG: KASAN: use-after-free in sock_wfree+0x118/0x120 >>> Read of size 8 at addr ffff880062da0060 by task a.out/4140 >>> >>> page:ffffea00018b6800 count:1 mapcount:0 mapping: (null) >>> index:0x0 compound_mapcount: 0 >>> flags: 0x100000000008100(slab|head) >>> raw: 0100000000008100 0000000000000000 0000000000000000 0000000180130013 >>> raw: dead000000000100 dead000000000200 ffff88006741f140 0000000000000000 >>> page dumped because: kasan: bad access detected >>> >>> CPU: 0 PID: 4140 Comm: a.out Not tainted 4.10.0-rc3+ #59 >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >>> Call Trace: >>> __dump_stack lib/dump_stack.c:15 >>> dump_stack+0x292/0x398 lib/dump_stack.c:51 >>> describe_address mm/kasan/report.c:262 >>> kasan_report_error+0x121/0x560 mm/kasan/report.c:370 >>> kasan_report mm/kasan/report.c:392 >>> __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:413 >>> sock_flag ./arch/x86/include/asm/bitops.h:324 >>> sock_wfree+0x118/0x120 net/core/sock.c:1631 >>> skb_release_head_state+0xfc/0x250 net/core/skbuff.c:655 >>> skb_release_all+0x15/0x60 net/core/skbuff.c:668 >>> __kfree_skb+0x15/0x20 net/core/skbuff.c:684 >>> kfree_skb+0x16e/0x4e0 net/core/skbuff.c:705 >>> inet_frag_destroy+0x121/0x290 net/ipv4/inet_fragment.c:304 >>> inet_frag_put ./include/net/inet_frag.h:133 >>> nf_ct_frag6_gather+0x1125/0x38b0 net/ipv6/netfilter/nf_conntrack_reasm.c:617 >>> ipv6_defrag+0x21b/0x350 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:68 >>> nf_hook_entry_hookfn ./include/linux/netfilter.h:102 >>> nf_hook_slow+0xc3/0x290 net/netfilter/core.c:310 >>> nf_hook ./include/linux/netfilter.h:212 >>> __ip6_local_out+0x52c/0xaf0 net/ipv6/output_core.c:160 >>> ip6_local_out+0x2d/0x170 net/ipv6/output_core.c:170 >>> ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1722 >>> ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1742 >>> rawv6_push_pending_frames net/ipv6/raw.c:613 >>> rawv6_sendmsg+0x2cff/0x4130 net/ipv6/raw.c:927 >>> inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744 >>> sock_sendmsg_nosec net/socket.c:635 >>> sock_sendmsg+0xca/0x110 net/socket.c:645 >>> sock_write_iter+0x326/0x620 net/socket.c:848 >>> new_sync_write fs/read_write.c:499 >>> __vfs_write+0x483/0x760 fs/read_write.c:512 >>> vfs_write+0x187/0x530 fs/read_write.c:560 >>> SYSC_write fs/read_write.c:607 >>> SyS_write+0xfb/0x230 fs/read_write.c:599 >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203 >>> RIP: 0033:0x7ff26e6f5b79 >>> RSP: 002b:00007ff268e0ed98 EFLAGS: 00000206 ORIG_RAX: 0000000000000001 >>> RAX: ffffffffffffffda RBX: 00007ff268e0f9c0 RCX: 00007ff26e6f5b79 >>> RDX: 0000000000000010 RSI: 0000000020f50fe1 RDI: 0000000000000003 >>> RBP: 00007ff26ebc1220 R08: 0000000000000000 R09: 0000000000000000 >>> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 >>> R13: 00007ff268e0f9c0 R14: 00007ff26efec040 R15: 0000000000000003 >>> >>> The buggy address belongs to the object at ffff880062da0000 >>> which belongs to the cache RAWv6 of size 1504 >>> The buggy address ffff880062da0060 is located 96 bytes inside >>> of 1504-byte region [ffff880062da0000, ffff880062da05e0) >>> >>> Freed by task 4113: >>> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 >>> save_stack+0x43/0xd0 mm/kasan/kasan.c:502 >>> set_track mm/kasan/kasan.c:514 >>> kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:578 >>> slab_free_hook mm/slub.c:1352 >>> slab_free_freelist_hook mm/slub.c:1374 >>> slab_free mm/slub.c:2951 >>> kmem_cache_free+0xb2/0x2c0 mm/slub.c:2973 >>> sk_prot_free net/core/sock.c:1377 >>> __sk_destruct+0x49c/0x6e0 net/core/sock.c:1452 >>> sk_destruct+0x47/0x80 net/core/sock.c:1460 >>> __sk_free+0x57/0x230 net/core/sock.c:1468 >>> sk_free+0x23/0x30 net/core/sock.c:1479 >>> sock_put ./include/net/sock.h:1638 >>> sk_common_release+0x31e/0x4e0 net/core/sock.c:2782 >>> rawv6_close+0x54/0x80 net/ipv6/raw.c:1214 >>> inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425 >>> inet6_release+0x50/0x70 net/ipv6/af_inet6.c:431 >>> sock_release+0x8d/0x1e0 net/socket.c:599 >>> sock_close+0x16/0x20 net/socket.c:1063 >>> __fput+0x332/0x7f0 fs/file_table.c:208 >>> ____fput+0x15/0x20 fs/file_table.c:244 >>> task_work_run+0x19b/0x270 kernel/task_work.c:116 >>> exit_task_work ./include/linux/task_work.h:21 >>> do_exit+0x186b/0x2800 kernel/exit.c:839 >>> do_group_exit+0x149/0x420 kernel/exit.c:943 >>> SYSC_exit_group kernel/exit.c:954 >>> SyS_exit_group+0x1d/0x20 kernel/exit.c:952 >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203 >>> >>> Allocated by task 4115: >>> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 >>> save_stack+0x43/0xd0 mm/kasan/kasan.c:502 >>> set_track mm/kasan/kasan.c:514 >>> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:605 >>> kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:544 >>> slab_post_alloc_hook mm/slab.h:432 >>> slab_alloc_node mm/slub.c:2708 >>> slab_alloc mm/slub.c:2716 >>> kmem_cache_alloc+0x1af/0x250 mm/slub.c:2721 >>> sk_prot_alloc+0x65/0x2a0 net/core/sock.c:1334 >>> sk_alloc+0x105/0x1010 net/core/sock.c:1396 >>> inet6_create+0x44d/0x1150 net/ipv6/af_inet6.c:183 >>> __sock_create+0x4f6/0x880 net/socket.c:1199 >>> sock_create net/socket.c:1239 >>> SYSC_socket net/socket.c:1269 >>> SyS_socket+0xf9/0x230 net/socket.c:1249 >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203 >>> >>> Memory state around the buggy address: >>> ffff880062d9ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >>> ffff880062d9ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >>>>ffff880062da0000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ^ >>> ffff880062da0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ffff880062da0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ================================================================== >> >> Sometimes this reproducer leads to another report: > > Looks very similar to issue fixed in 8282f27449bf15548cb82c77b6e04ee0ab827bdc > > Could you try : Hi Eric, This patch fixes the issue. Thanks! > > diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c > b/net/ipv6/netfilter/nf_conntrack_reasm.c > index 9948b5ce52dad3a823edede517f17069bd7226dc..986d4ca38832b17703b09e50209ec133885c7276 > 100644 > --- a/net/ipv6/netfilter/nf_conntrack_reasm.c > +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c > @@ -589,6 +589,7 @@ int nf_ct_frag6_gather(struct net *net, struct > sk_buff *skb, u32 user) > hdr = ipv6_hdr(skb); > fhdr = (struct frag_hdr *)skb_transport_header(skb); > > + skb_orphan(skb); > fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr, > skb->dev ? skb->dev->ifindex : 0, ip6_frag_ecn(hdr)); > if (fq == NULL) { > diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c > index 6b78bab27755b2758f3c8ecd5b9c6d61615af4b6..fdec2a4cc559ab956c58d26535bdf010c0a8964a > 100644 > --- a/net/openvswitch/conntrack.c > +++ b/net/openvswitch/conntrack.c > @@ -367,7 +367,6 @@ static int handle_fragments(struct net *net, > struct sw_flow_key *key, > } else if (key->eth.type == htons(ETH_P_IPV6)) { > enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone; > > - skb_orphan(skb); > memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); > err = nf_ct_frag6_gather(net, skb, user); > if (err) {
On Mon, Jan 9, 2017 at 11:06 AM, Andrey Konovalov <andreyknvl@google.com> wrote: > > Hi Eric, > > This patch fixes the issue. > > Thanks! Thanks Andrey. Could you please post your .config for next KASAN reports ? I am asking this because I could not reproduce the issue with my own builds, so I had to guess but could not test the fix myself. Thanks !
On Mon, Jan 9, 2017 at 8:08 PM, Eric Dumazet <edumazet@google.com> wrote: > On Mon, Jan 9, 2017 at 11:06 AM, Andrey Konovalov <andreyknvl@google.com> wrote: >> >> Hi Eric, >> >> This patch fixes the issue. >> >> Thanks! > > Thanks Andrey. > > Could you please post your .config for next KASAN reports ? Sure, no problem! > > I am asking this because I could not reproduce the issue with my own > builds, so I had to guess but could not test the fix myself. > > Thanks !
On Mon, Jan 9, 2017 at 6:21 PM, Eric Dumazet <edumazet@google.com> wrote: > On Mon, Jan 9, 2017 at 9:11 AM, Andrey Konovalov <andreyknvl@google.com> wrote: >> On Mon, Jan 9, 2017 at 6:08 PM, Andrey Konovalov <andreyknvl@google.com> wrote: >>> Hi! >>> >>> I've got the following error report while running the syzkaller fuzzer. >>> >>> On commit a121103c922847ba5010819a3f250f1f7fc84ab8 (4.10-rc3). >>> >>> A reproducer is attached. >>> >>> ================================================================== >>> BUG: KASAN: use-after-free in sock_wfree+0x118/0x120 >>> Read of size 8 at addr ffff880062da0060 by task a.out/4140 >>> >>> page:ffffea00018b6800 count:1 mapcount:0 mapping: (null) >>> index:0x0 compound_mapcount: 0 >>> flags: 0x100000000008100(slab|head) >>> raw: 0100000000008100 0000000000000000 0000000000000000 0000000180130013 >>> raw: dead000000000100 dead000000000200 ffff88006741f140 0000000000000000 >>> page dumped because: kasan: bad access detected >>> >>> CPU: 0 PID: 4140 Comm: a.out Not tainted 4.10.0-rc3+ #59 >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >>> Call Trace: >>> __dump_stack lib/dump_stack.c:15 >>> dump_stack+0x292/0x398 lib/dump_stack.c:51 >>> describe_address mm/kasan/report.c:262 >>> kasan_report_error+0x121/0x560 mm/kasan/report.c:370 >>> kasan_report mm/kasan/report.c:392 >>> __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:413 >>> sock_flag ./arch/x86/include/asm/bitops.h:324 >>> sock_wfree+0x118/0x120 net/core/sock.c:1631 >>> skb_release_head_state+0xfc/0x250 net/core/skbuff.c:655 >>> skb_release_all+0x15/0x60 net/core/skbuff.c:668 >>> __kfree_skb+0x15/0x20 net/core/skbuff.c:684 >>> kfree_skb+0x16e/0x4e0 net/core/skbuff.c:705 >>> inet_frag_destroy+0x121/0x290 net/ipv4/inet_fragment.c:304 >>> inet_frag_put ./include/net/inet_frag.h:133 >>> nf_ct_frag6_gather+0x1125/0x38b0 net/ipv6/netfilter/nf_conntrack_reasm.c:617 >>> ipv6_defrag+0x21b/0x350 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:68 >>> nf_hook_entry_hookfn ./include/linux/netfilter.h:102 >>> nf_hook_slow+0xc3/0x290 net/netfilter/core.c:310 >>> nf_hook ./include/linux/netfilter.h:212 >>> __ip6_local_out+0x52c/0xaf0 net/ipv6/output_core.c:160 >>> ip6_local_out+0x2d/0x170 net/ipv6/output_core.c:170 >>> ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1722 >>> ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1742 >>> rawv6_push_pending_frames net/ipv6/raw.c:613 >>> rawv6_sendmsg+0x2cff/0x4130 net/ipv6/raw.c:927 >>> inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744 >>> sock_sendmsg_nosec net/socket.c:635 >>> sock_sendmsg+0xca/0x110 net/socket.c:645 >>> sock_write_iter+0x326/0x620 net/socket.c:848 >>> new_sync_write fs/read_write.c:499 >>> __vfs_write+0x483/0x760 fs/read_write.c:512 >>> vfs_write+0x187/0x530 fs/read_write.c:560 >>> SYSC_write fs/read_write.c:607 >>> SyS_write+0xfb/0x230 fs/read_write.c:599 >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203 >>> RIP: 0033:0x7ff26e6f5b79 >>> RSP: 002b:00007ff268e0ed98 EFLAGS: 00000206 ORIG_RAX: 0000000000000001 >>> RAX: ffffffffffffffda RBX: 00007ff268e0f9c0 RCX: 00007ff26e6f5b79 >>> RDX: 0000000000000010 RSI: 0000000020f50fe1 RDI: 0000000000000003 >>> RBP: 00007ff26ebc1220 R08: 0000000000000000 R09: 0000000000000000 >>> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 >>> R13: 00007ff268e0f9c0 R14: 00007ff26efec040 R15: 0000000000000003 >>> >>> The buggy address belongs to the object at ffff880062da0000 >>> which belongs to the cache RAWv6 of size 1504 >>> The buggy address ffff880062da0060 is located 96 bytes inside >>> of 1504-byte region [ffff880062da0000, ffff880062da05e0) >>> >>> Freed by task 4113: >>> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 >>> save_stack+0x43/0xd0 mm/kasan/kasan.c:502 >>> set_track mm/kasan/kasan.c:514 >>> kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:578 >>> slab_free_hook mm/slub.c:1352 >>> slab_free_freelist_hook mm/slub.c:1374 >>> slab_free mm/slub.c:2951 >>> kmem_cache_free+0xb2/0x2c0 mm/slub.c:2973 >>> sk_prot_free net/core/sock.c:1377 >>> __sk_destruct+0x49c/0x6e0 net/core/sock.c:1452 >>> sk_destruct+0x47/0x80 net/core/sock.c:1460 >>> __sk_free+0x57/0x230 net/core/sock.c:1468 >>> sk_free+0x23/0x30 net/core/sock.c:1479 >>> sock_put ./include/net/sock.h:1638 >>> sk_common_release+0x31e/0x4e0 net/core/sock.c:2782 >>> rawv6_close+0x54/0x80 net/ipv6/raw.c:1214 >>> inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425 >>> inet6_release+0x50/0x70 net/ipv6/af_inet6.c:431 >>> sock_release+0x8d/0x1e0 net/socket.c:599 >>> sock_close+0x16/0x20 net/socket.c:1063 >>> __fput+0x332/0x7f0 fs/file_table.c:208 >>> ____fput+0x15/0x20 fs/file_table.c:244 >>> task_work_run+0x19b/0x270 kernel/task_work.c:116 >>> exit_task_work ./include/linux/task_work.h:21 >>> do_exit+0x186b/0x2800 kernel/exit.c:839 >>> do_group_exit+0x149/0x420 kernel/exit.c:943 >>> SYSC_exit_group kernel/exit.c:954 >>> SyS_exit_group+0x1d/0x20 kernel/exit.c:952 >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203 >>> >>> Allocated by task 4115: >>> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 >>> save_stack+0x43/0xd0 mm/kasan/kasan.c:502 >>> set_track mm/kasan/kasan.c:514 >>> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:605 >>> kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:544 >>> slab_post_alloc_hook mm/slab.h:432 >>> slab_alloc_node mm/slub.c:2708 >>> slab_alloc mm/slub.c:2716 >>> kmem_cache_alloc+0x1af/0x250 mm/slub.c:2721 >>> sk_prot_alloc+0x65/0x2a0 net/core/sock.c:1334 >>> sk_alloc+0x105/0x1010 net/core/sock.c:1396 >>> inet6_create+0x44d/0x1150 net/ipv6/af_inet6.c:183 >>> __sock_create+0x4f6/0x880 net/socket.c:1199 >>> sock_create net/socket.c:1239 >>> SYSC_socket net/socket.c:1269 >>> SyS_socket+0xf9/0x230 net/socket.c:1249 >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203 >>> >>> Memory state around the buggy address: >>> ffff880062d9ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >>> ffff880062d9ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >>>>ffff880062da0000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ^ >>> ffff880062da0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ffff880062da0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ================================================================== >> >> Sometimes this reproducer leads to another report: > > Looks very similar to issue fixed in 8282f27449bf15548cb82c77b6e04ee0ab827bdc > > Could you try : > > diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c > b/net/ipv6/netfilter/nf_conntrack_reasm.c > index 9948b5ce52dad3a823edede517f17069bd7226dc..986d4ca38832b17703b09e50209ec133885c7276 > 100644 > --- a/net/ipv6/netfilter/nf_conntrack_reasm.c > +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c > @@ -589,6 +589,7 @@ int nf_ct_frag6_gather(struct net *net, struct > sk_buff *skb, u32 user) > hdr = ipv6_hdr(skb); > fhdr = (struct frag_hdr *)skb_transport_header(skb); > > + skb_orphan(skb); > fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr, > skb->dev ? skb->dev->ifindex : 0, ip6_frag_ecn(hdr)); > if (fq == NULL) { > diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c > index 6b78bab27755b2758f3c8ecd5b9c6d61615af4b6..fdec2a4cc559ab956c58d26535bdf010c0a8964a > 100644 > --- a/net/openvswitch/conntrack.c > +++ b/net/openvswitch/conntrack.c > @@ -367,7 +367,6 @@ static int handle_fragments(struct net *net, > struct sw_flow_key *key, > } else if (key->eth.type == htons(ETH_P_IPV6)) { > enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone; > > - skb_orphan(skb); > memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); > err = nf_ct_frag6_gather(net, skb, user); > if (err) { Hi Eric, I'm still seeing these reports on 926af6273fc683cd98cd0ce7bf0d04a02eed6742. Did you mail the patch? Thanks!
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index 9948b5ce52dad3a823edede517f17069bd7226dc..986d4ca38832b17703b09e50209ec133885c7276 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -589,6 +589,7 @@ int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user) hdr = ipv6_hdr(skb); fhdr = (struct frag_hdr *)skb_transport_header(skb); + skb_orphan(skb); fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr, skb->dev ? skb->dev->ifindex : 0, ip6_frag_ecn(hdr)); if (fq == NULL) { diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c index 6b78bab27755b2758f3c8ecd5b9c6d61615af4b6..fdec2a4cc559ab956c58d26535bdf010c0a8964a 100644 --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -367,7 +367,6 @@ static int handle_fragments(struct net *net, struct sw_flow_key *key, } else if (key->eth.type == htons(ETH_P_IPV6)) { enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone; - skb_orphan(skb); memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); err = nf_ct_frag6_gather(net, skb, user);