random: cc1: uninitialized urandom read (8 bytes read) audit: type=1400 audit(1542601418.614:9): avc: denied { map } for pid=1786 comm="syz-execprog" path="/root/syzkaller-shm812481192" dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1542601424.184:10): avc: denied { prog_load } for pid=4156 comm="syz-executor2" 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 ____bpf_skb_change_tail net/core/filter.c:2370 [inline] BUG: KASAN: slab-out-of-bounds in bpf_skb_change_tail+0xa2c/0xb90 net/core/filter.c:2367 Read of size 8 at addr ffff8801c7c57e10 by task syz-executor2/4162 CPU: 0 PID: 4162 Comm: syz-executor2 Not tainted 4.14.81+ #6 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 ____bpf_skb_change_tail net/core/filter.c:2370 [inline] bpf_skb_change_tail+0xa2c/0xb90 net/core/filter.c:2367 ___bpf_prog_run+0x248e/0x5c70 kernel/bpf/core.c:1012 Allocated by task 350: 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 getname_flags+0xc4/0x540 fs/namei.c:138 getname fs/namei.c:209 [inline] do_unlinkat+0xc9/0x650 fs/namei.c:4070 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 350: 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 putname+0xcf/0x100 fs/namei.c:259 do_unlinkat+0x16c/0x650 fs/namei.c:4113 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 ffff8801c7c56600 which belongs to the cache names_cache of size 4096 The buggy address is located 2064 bytes to the right of 4096-byte region [ffff8801c7c56600, ffff8801c7c57600) The buggy address belongs to the page: page:ffffea00071f1400 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 flags: 0x4000000000008100(slab|head) raw: 4000000000008100 0000000000000000 0000000000000000 0000000100070007 raw: dead000000000100 dead000000000200 ffff8801da97e000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801c7c57d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801c7c57d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8801c7c57e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff8801c7c57e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801c7c57f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================