syzbot


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

Status: fixed on 2018/01/22 13:19
Subsystems: bpf
[Documentation on labels]
Fix commit: bbeb6e4323da bpf, array: fix overflow in max_entries and undefined behavior in index_mask
First crash: 2324d, last: 2320d

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in __read_once_size include/linux/compiler.h:183 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_fd_array_map_lookup_elem+0x440/0x4c0 kernel/bpf/arraymap.c:374
Read of size 8 at addr ffff8801ccf3f9b8 by task syz-executor1/13671

CPU: 1 PID: 13671 Comm: syz-executor1 Not tainted 4.15.0-rc8+ #263
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+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 __read_once_size include/linux/compiler.h:183 [inline]
 bpf_fd_array_map_lookup_elem+0x440/0x4c0 kernel/bpf/arraymap.c:374
 map_lookup_elem+0x6b5/0xbd0 kernel/bpf/syscall.c:577
 SYSC_bpf kernel/bpf/syscall.c:1711 [inline]
 SyS_bpf+0x922/0x4400 kernel/bpf/syscall.c:1685
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452cf9
RSP: 002b:00007fde6a56bc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452cf9
RDX: 0000000000000018 RSI: 00000000206d1fe8 RDI: 0000000000000001
RBP: 0000000000000037 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ee5c8
R13: 00000000ffffffff R14: 00007fde6a56c6d4 R15: 0000000000000000

Allocated by task 16727:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3708 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3717
 kmalloc include/linux/slab.h:504 [inline]
 kzalloc include/linux/slab.h:688 [inline]
 __proc_create+0x21a/0x880 fs/proc/generic.c:366
 proc_create_data+0x76/0x180 fs/proc/generic.c:488
 snmp6_register_dev+0xc3/0x150 net/ipv6/proc.c:296
 ipv6_add_dev+0x61f/0x12f0 net/ipv6/addrconf.c:420
 addrconf_notify+0x1b14/0x2270 net/ipv6/addrconf.c:3432
 notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x32/0x60 net/core/dev.c:1691
 call_netdevice_notifiers net/core/dev.c:1709 [inline]
 dev_open+0x147/0x180 net/core/dev.c:1432
 ipmr_new_tunnel+0x499/0x640 net/ipv4/ipmr.c:482
 vif_add+0x54c/0x1290 net/ipv4/ipmr.c:903
 ip_mroute_setsockopt+0xbc7/0xf20 net/ipv4/ipmr.c:1518
 do_ip_setsockopt.isra.12+0x2a7/0x3160 net/ipv4/ip_sockglue.c:641
 ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1248
 raw_setsockopt+0xb7/0xd0 net/ipv4/raw.c:857
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2968
 SYSC_setsockopt net/socket.c:1831 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1810
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 3728:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3488 [inline]
 kfree+0xd6/0x260 mm/slab.c:3803
 seq_release+0x59/0x70 fs/seq_file.c:366
 kernfs_fop_release+0x10b/0x180 fs/kernfs/file.c:781
 __fput+0x327/0x7e0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x9e/0xa0

The buggy address belongs to the object at ffff8801ccf3f8c0
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 248 bytes inside of
 256-byte region [ffff8801ccf3f8c0, ffff8801ccf3f9c0)
The buggy address belongs to the page:
page:ffffea000733cfc0 count:1 mapcount:0 mapping:ffff8801ccf3f000 index:0xffff8801ccf3f3c0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801ccf3f000 ffff8801ccf3f3c0 0000000100000009
raw: ffffea0006fc8160 ffffea00071970a0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ccf3f880: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff8801ccf3f900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801ccf3f980: 00 07 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                        ^
 ffff8801ccf3fa00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801ccf3fa80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/01/15 17:40 upstream a8750ddca918 66d492a6 .config console log report ci-upstream-kasan-gce
2018/01/14 04:28 upstream 2c1cfa499018 c9e7aeae .config console log report ci-upstream-kasan-gce
2018/01/14 03:37 net-next-old 6bd39bc3da0f c9e7aeae .config console log report ci-upstream-net-kasan-gce
2018/01/13 20:31 net-next-old 6bd39bc3da0f c9e7aeae .config console log report ci-upstream-net-kasan-gce
2018/01/12 11:02 mmots 2c405fa05106 9dc808a6 .config console log report ci-upstream-mmots-kasan-gce
2018/01/12 03:40 mmots 2c405fa05106 9dc808a6 .config console log report ci-upstream-mmots-kasan-gce
2018/01/11 16:44 mmots 4147d50978df 9dc808a6 .config console log report ci-upstream-mmots-kasan-gce
* Struck through repros no longer work on HEAD.