syzbot

random: sshd: uninitialized urandom read (32 bytes read)
audit: type=1400 audit(1538537154.149:7): avc:  denied  { map } for  pid=1794 comm="syz-executor525" path="/root/syz-executor525565252" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
audit: type=1400 audit(1538537154.169:8): avc:  denied  { prog_load } for  pid=1794 comm="syz-executor525" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=bpf permissive=1
audit: type=1400 audit(1538537154.199:9): avc:  denied  { prog_run } for  pid=1794 comm="syz-executor525" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=bpf permissive=1
==================================================================
BUG: KASAN: slab-out-of-bounds in skb_at_tc_ingress include/net/sch_generic.h:452 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_push_mac_rcsum net/core/filter.c:1422 [inline]
BUG: KASAN: slab-out-of-bounds in ____bpf_skb_vlan_push net/core/filter.c:1969 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_skb_vlan_push+0x45e/0x540 net/core/filter.c:1960
Read of size 4 at addr ffff8801d0ef0c48 by task syz-executor525/1794

CPU: 1 PID: 1794 Comm: syz-executor525 Not tainted 4.14.73+ #14
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x11b lib/dump_stack.c:53
 print_address_description+0x60/0x22b mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report.cold.6+0x11b/0x2dd mm/kasan/report.c:409
 skb_at_tc_ingress include/net/sch_generic.h:452 [inline]
 bpf_push_mac_rcsum net/core/filter.c:1422 [inline]
 ____bpf_skb_vlan_push net/core/filter.c:1969 [inline]
 bpf_skb_vlan_push+0x45e/0x540 net/core/filter.c:1960
 ___bpf_prog_run+0x248e/0x5c70 kernel/bpf/core.c:1012

Allocated by task 230:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.1+0x4f/0xd0 mm/kasan/kasan.c:551
 slab_post_alloc_hook mm/slab.h:442 [inline]
 slab_alloc_node mm/slub.c:2723 [inline]
 slab_alloc mm/slub.c:2731 [inline]
 kmem_cache_alloc+0xe4/0x2b0 mm/slub.c:2736
 kmem_cache_alloc_node include/linux/slab.h:361 [inline]
 __alloc_skb+0xd8/0x550 net/core/skbuff.c:193
 alloc_skb include/linux/skbuff.h:980 [inline]
 alloc_skb_with_frags+0xab/0x500 net/core/skbuff.c:5167
 sock_alloc_send_pskb+0x55e/0x6e0 net/core/sock.c:2075
 unix_dgram_sendmsg+0x37b/0xf50 net/unix/af_unix.c:1681
 sock_sendmsg_nosec net/socket.c:645 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:655
 SYSC_sendto net/socket.c:1762 [inline]
 SyS_sendto+0x211/0x340 net/socket.c:1730
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 191:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:524
 slab_free_hook mm/slub.c:1389 [inline]
 slab_free_freelist_hook mm/slub.c:1410 [inline]
 slab_free mm/slub.c:2966 [inline]
 kmem_cache_free+0x12d/0x350 mm/slub.c:2988
 kfree_skbmem+0x9e/0x100 net/core/skbuff.c:582
 __kfree_skb net/core/skbuff.c:642 [inline]
 consume_skb+0xc9/0x330 net/core/skbuff.c:701
 skb_free_datagram+0x15/0xd0 net/core/datagram.c:331
 unix_dgram_recvmsg+0x762/0xd20 net/unix/af_unix.c:2183
 sock_recvmsg_nosec net/socket.c:818 [inline]
 sock_recvmsg+0xc0/0x100 net/socket.c:825
 SYSC_recvfrom net/socket.c:1814 [inline]
 SyS_recvfrom+0x1d2/0x310 net/socket.c:1786
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801d0ef0b40
 which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 40 bytes to the right of
 224-byte region [ffff8801d0ef0b40, ffff8801d0ef0c20)
The buggy address belongs to the page:
page:ffffea000743bc00 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000100(slab)
raw: 4000000000000100 0000000000000000 0000000000000000 00000001800c000c
raw: 0000000000000000 0000000100000001 ffff8801dab70200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d0ef0b00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801d0ef0b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801d0ef0c00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
                                              ^
 ffff8801d0ef0c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d0ef0d00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================