KASAN: use-after-free Read in bpf_prog_kallsyms

KASAN: use-after-free Read in bpf_prog_kallsyms_add
Status: upstream: reported on 2019/09/02 18:26
Reported-by: syzbot+7ef6f45e029aa6590abb@syzkaller.appspotmail.com
First crash: 74d, last: 74d

similar bugs (2):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
upstream	KASAN: use-after-free Read in bpf_prog_kallsyms_add	syz	cause+fix	120	197d	431d	13/14	fixed on 2019/09/06 20:45
linux-4.19	KASAN: use-after-free Read in bpf_prog_kallsyms_add			2	60d	122d	0/1	upstream: reported on 2019/07/16 17:11

Sample crash report:

==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:183 [inline]
BUG: KASAN: use-after-free in list_empty include/linux/list.h:203 [inline]
BUG: KASAN: use-after-free in bpf_prog_ksym_node_add kernel/bpf/core.c:369 [inline]
BUG: KASAN: use-after-free in bpf_prog_kallsyms_add+0x735/0x7b0 kernel/bpf/core.c:401
Read of size 8 at addr ffff8880a72b8148 by task syz-executor.3/20056
netlink: 11 bytes leftover after parsing attributes in process `syz-executor.1'.

CPU: 1 PID: 20056 Comm: syz-executor.3 Not tainted 4.14.141 #37
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+0x138/0x197 lib/dump_stack.c:53
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 __read_once_size include/linux/compiler.h:183 [inline]
 list_empty include/linux/list.h:203 [inline]
 bpf_prog_ksym_node_add kernel/bpf/core.c:369 [inline]
 bpf_prog_kallsyms_add+0x735/0x7b0 kernel/bpf/core.c:401
 bpf_prog_load+0x78f/0xf30 kernel/bpf/syscall.c:1082
 SYSC_bpf kernel/bpf/syscall.c:1503 [inline]
 SyS_bpf+0x433/0x2da8 kernel/bpf/syscall.c:1469
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459879
RSP: 002b:00007face409bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459879
RDX: 0000000000000048 RSI: 00000000200054c0 RDI: 0000000000000005
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007face409c6d4
R13: 00000000004bfcdc R14: 00000000004d19d8 R15: 00000000ffffffff

Allocated by task 20056:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 kmem_cache_alloc_trace+0x152/0x790 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 bpf_prog_alloc+0x180/0x1e0 kernel/bpf/core.c:89
 bpf_prog_load+0x292/0xf30 kernel/bpf/syscall.c:1030
 SYSC_bpf kernel/bpf/syscall.c:1503 [inline]
 SyS_bpf+0x433/0x2da8 kernel/bpf/syscall.c:1469
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 18:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcc/0x270 mm/slab.c:3815
 bpf_jit_free+0x89/0x310
 bpf_prog_free_deferred+0x31/0x40 kernel/bpf/core.c:1480
 process_one_work+0x863/0x1600 kernel/workqueue.c:2114
 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff8880a72b8100
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 72 bytes inside of
 192-byte region [ffff8880a72b8100, ffff8880a72b81c0)
The buggy address belongs to the page:
page:ffffea00029cae00 count:1 mapcount:0 mapping:ffff8880a72b8000 index:0xffff8880a72b8200
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff8880a72b8000 ffff8880a72b8200 000000010000000c
raw: ffffea00017c1060 ffffea00028385a0 ffff8880aa800040 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
kobject: 'kvm' (ffff8880a71ac010): fill_kobj_path: path = '/devices/virtual/misc/kvm'
 ffff8880a72b8000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880a72b8080: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a72b8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8880a72b8180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880a72b8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci2-linux-4-14	2019/09/02 17:25	linux-4.14.y	01fd1694	14544a56	.config	log	report			ast@kernel.org, daniel@iogearbox.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org