syzbot


KASAN: use-after-free Read in __bpf_prog_put

Status: fixed on 2018/02/01 10:32
Subsystems: bpf
[Documentation on labels]
Reported-by: syzbot+d85bfb332db8f0794212@syzkaller.appspotmail.com
Fix commit: bbeb6e4323da bpf, array: fix overflow in max_entries and undefined behavior in index_mask
First crash: 2327d, last: 2327d
Discussions (1)
Title Replies (including bot) Last reply
KASAN: use-after-free Read in __bpf_prog_put 3 (4) 2018/01/31 01:52

Sample crash report:
netlink: 3 bytes leftover after parsing attributes in process `syz-executor5'.
==================================================================
BUG: KASAN: use-after-free in __bpf_prog_put+0x5e8/0x640 kernel/bpf/syscall.c:944
netlink: 'syz-executor5': attribute type 5 has an invalid length.
Read of size 8 at addr ffff8801d3619658 by task syz-executor0/12398

CPU: 1 PID: 12398 Comm: syz-executor0 Not tainted 4.15.0-rc7-mm1+ #53
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:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __bpf_prog_put+0x5e8/0x640 kernel/bpf/syscall.c:944
 bpf_prog_put+0x1a/0x20 kernel/bpf/syscall.c:961
 prog_fd_array_put_ptr+0x15/0x20 kernel/bpf/arraymap.c:446
 fd_array_map_delete_elem+0xc8/0x110 kernel/bpf/arraymap.c:420
 map_delete_elem kernel/bpf/syscall.c:737 [inline]
 SYSC_bpf kernel/bpf/syscall.c:1814 [inline]
 SyS_bpf+0x22ea/0x4400 kernel/bpf/syscall.c:1782
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452ac9
RSP: 002b:00007fb70df60c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 0000000000000010 RSI: 0000000020f02ff0 RDI: 0000000000000003
RBP: 00000000000003aa R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f3890
R13: 00000000ffffffff R14: 00007fb70df616d4 R15: 0000000000000000

Allocated by task 11996:
 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:552
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3541
 kmem_cache_zalloc include/linux/slab.h:694 [inline]
 get_empty_filp+0xfb/0x4f0 fs/file_table.c:122
 path_openat+0xed/0x3530 fs/namei.c:3514
 do_filp_open+0x25b/0x3b0 fs/namei.c:3572
 do_sys_open+0x502/0x6d0 fs/open.c:1059
 SYSC_open fs/open.c:1077 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1072
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 11994:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kmem_cache_free+0x86/0x2b0 mm/slab.c:3743
 file_free_rcu+0x5c/0x70 fs/file_table.c:49
 __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
 rcu_do_batch kernel/rcu/tree.c:2675 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2934 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2901 [inline]
 rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2918
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801d36195c0
 which belongs to the cache filp of size 456
The buggy address is located 152 bytes inside of
 456-byte region [ffff8801d36195c0, ffff8801d3619788)
The buggy address belongs to the page:
page:ffffea00074d8640 count:1 mapcount:0 mapping:ffff8801d36190c0 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d36190c0 0000000000000000 0000000100000006
raw: ffffea00074c49a0 ffffea000747a160 ffff8801dae30180 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d3619500: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801d3619580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8801d3619600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8801d3619680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d3619700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/01/11 10:02 mmots 4147d50978df 02a19b64 .config console log report ci-upstream-mmots-kasan-gce
* Struck through repros no longer work on HEAD.