KASAN: slab-out-of-bounds Read in decode

KASAN: slab-out-of-bounds Read in decode_session6
Status: upstream: reported on 2020/06/27 07:18
Reported-by: syzbot+2bcc71839223ec82f056@syzkaller.appspotmail.com
First crash: 9d23h, last: 2d05h

Sample crash report:

==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3389
Read of size 1 at addr ffff8880677e36ce by task syz-executor.5/6666

CPU: 1 PID: 6666 Comm: syz-executor.5 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 decode_session6+0xe7c/0x1580 net/xfrm/xfrm_policy.c:3389
 __xfrm_decode_session+0x50/0xb0 net/xfrm/xfrm_policy.c:3481
 xfrm_decode_session include/net/xfrm.h:1134 [inline]
 vti6_tnl_xmit+0x40d/0x1c80 net/ipv6/ip6_vti.c:577
 __netdev_start_xmit include/linux/netdevice.h:4611 [inline]
 netdev_start_xmit include/linux/netdevice.h:4625 [inline]
 xmit_one net/core/dev.c:3556 [inline]
 dev_hard_start_xmit+0x193/0x950 net/core/dev.c:3572
 sch_direct_xmit+0x2ea/0xc00 net/sched/sch_generic.c:313
 qdisc_restart net/sched/sch_generic.c:376 [inline]
 __qdisc_run+0x4b9/0x1630 net/sched/sch_generic.c:384
 __dev_xmit_skb net/core/dev.c:3795 [inline]
 __dev_queue_xmit+0x1995/0x2d60 net/core/dev.c:4100
 neigh_connected_output+0x299/0x370 net/core/neighbour.c:1518
 neigh_output include/net/neighbour.h:509 [inline]
 ip6_finish_output2+0x8b6/0x17b0 net/ipv6/ip6_output.c:117
 __ip6_finish_output net/ipv6/ip6_output.c:143 [inline]
 __ip6_finish_output+0x447/0xab0 net/ipv6/ip6_output.c:128
 ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:176
 dst_output include/net/dst.h:435 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ndisc_send_skb+0xa69/0x1720 net/ipv6/ndisc.c:506
 ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:648
 ndisc_solicit+0x2cd/0x450 net/ipv6/ndisc.c:740
 neigh_probe+0xc2/0x110 net/core/neighbour.c:1009
 neigh_timer_handler+0x5f0/0x1150 net/core/neighbour.c:1091
 call_timer_fn+0x1ac/0x760 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers.part.0+0x54c/0xa20 kernel/time/timer.c:1773
 __run_timers kernel/time/timer.c:1745 [inline]
 run_timer_softirq+0xae/0x1a0 kernel/time/timer.c:1786
 __do_softirq+0x34c/0xa60 kernel/softirq.c:292
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 do_softirq_own_stack+0x111/0x170 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:387 [inline]
 __irq_exit_rcu kernel/softirq.c:417 [inline]
 irq_exit_rcu+0x229/0x270 kernel/softirq.c:429
 sysvec_apic_timer_interrupt+0x12d/0x220 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:162 [inline]
RIP: 0010:unwind_next_frame+0x238/0x1f90 arch/x86/kernel/unwind_orc.c:446
Code: ff 39 d6 0f 83 54 12 00 00 48 ba 00 00 00 00 00 fc ff df 41 89 f0 4a 8d 3c 85 b4 35 9a 8b 49 89 f9 49 c1 e9 03 45 0f b6 0c 11 <48> 89 fa 83 e2 07 83 c2 03 44 38 ca 7c 32 45 84 c9 74 2d 4c 89 44
RSP: 0018:ffffc90005faf4f0 EFLAGS: 00000a07
RAX: 0000000000000000 RBX: 1ffff92000bf5ea6 RCX: ffffffff812b403d
RDX: dffffc0000000000 RSI: 0000000000002b40 RDI: ffffffff8b9ae2b4
RBP: 0000000000000001 R08: 0000000000002b40 R09: 0000000000000000
R10: 000000000007201e R11: 0000000000000001 R12: ffffc90005faf660
R13: ffffc90005faf64d R14: ffffc90005faf668 R15: ffffc90005faf618
 __unwind_start+0x4dd/0x7c0 arch/x86/kernel/unwind_orc.c:698
 unwind_start arch/x86/include/asm/unwind.h:60 [inline]
 arch_stack_walk+0x5e/0xf0 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 slab_post_alloc_hook mm/slab.h:586 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc_trace+0x136/0x2d0 mm/slab.c:3549
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 alloc_group_attrs+0x1d4/0x2f0 drivers/infiniband/core/sysfs.c:743
 add_port drivers/infiniband/core/sysfs.c:1109 [inline]
 ib_setup_port_attrs+0x8cb/0x12f0 drivers/infiniband/core/sysfs.c:1345
 add_one_compat_dev+0x4ab/0x800 drivers/infiniband/core/device.c:918
 rdma_dev_init_net+0x2dc/0x480 drivers/infiniband/core/device.c:1134
 ops_init+0xaf/0x470 net/core/net_namespace.c:151
 setup_net+0x2d8/0x850 net/core/net_namespace.c:341
 copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
 create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
 ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
 __do_sys_unshare kernel/fork.c:3051 [inline]
 __se_sys_unshare kernel/fork.c:3049 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb29
Code: Bad RIP value.
RSP: 002b:00007f76a4e51c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 000000000050ba20 RCX: 000000000045cb29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000c8f R14: 00000000004ceebe R15: 00007f76a4e526d4

Allocated by task 3878:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 slab_post_alloc_hook mm/slab.h:586 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x12c/0x3b0 mm/slab.c:3484
 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
 getname_flags fs/namei.c:2646 [inline]
 user_path_at_empty+0xa1/0x100 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 vfs_statx+0x14e/0x390 fs/stat.c:202
 vfs_lstat include/linux/fs.h:3301 [inline]
 __do_sys_newlstat+0x91/0x110 fs/stat.c:374
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 3878:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kmem_cache_free+0x7f/0x310 mm/slab.c:3694
 putname+0xe1/0x120 fs/namei.c:259
 filename_lookup+0x3b1/0x560 fs/namei.c:2376
 user_path_at include/linux/namei.h:59 [inline]
 vfs_statx+0x14e/0x390 fs/stat.c:202
 vfs_lstat include/linux/fs.h:3301 [inline]
 __do_sys_newlstat+0x91/0x110 fs/stat.c:374
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880677e2280
 which belongs to the cache names_cache of size 4096
The buggy address is located 1102 bytes to the right of
 4096-byte region [ffff8880677e2280, ffff8880677e3280)
The buggy address belongs to the page:
page:ffffea00019df880 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea00019df880 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea00019df808 ffffea00019df988 ffff8880aa1d0000
raw: 0000000000000000 ffff8880677e2280 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880677e3580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880677e3600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880677e3680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                              ^
 ffff8880677e3700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880677e3780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (5):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Maintainers
ci-upstream-net-this-kasan-gce	2020/07/02 16:29	net	e4b9a72d	bed10395	.config	log	report	davem@davemloft.net, herbert@gondor.apana.org.au, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, steffen.klassert@secunet.com
ci-upstream-net-this-kasan-gce	2020/06/29 14:51	net	0574e200	a2cdad9d	.config	log	report	davem@davemloft.net, herbert@gondor.apana.org.au, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, steffen.klassert@secunet.com
ci-upstream-net-this-kasan-gce	2020/06/28 11:50	net	4a21185c	ffec44b5	.config	log	report	davem@davemloft.net, herbert@gondor.apana.org.au, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, steffen.klassert@secunet.com
ci-upstream-net-this-kasan-gce	2020/06/27 18:33	net	4a21185c	ffec44b5	.config	log	report	davem@davemloft.net, herbert@gondor.apana.org.au, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, steffen.klassert@secunet.com
ci-upstream-net-this-kasan-gce	2020/06/24 22:18	net	b835a71e	54566aff	.config	log	report	davem@davemloft.net, herbert@gondor.apana.org.au, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, steffen.klassert@secunet.com