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

KASAN: slab-out-of-bounds Read in bpf_clone_redirect
Status: fixed on 2020/01/28 16:29
Reported-by: syzbot+24bc05f38b3e3dda58ea@syzkaller.appspotmail.com
Fix commit: 7fed98f4 bpf: reject passing modified ctx to helper functions
First crash: 310d, last: 147d

Fix bisection: fixed by (bisect log):

commit 7fed98f4a1e6eb77a5d66ecfdf9345e21df6ac82
Author: Daniel Borkmann <daniel@iogearbox.net>
Date: Thu Jun 7 15:40:03 2018 +0000

bpf: reject passing modified ctx to helper functions

similar bugs (1):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
android-414	KASAN: slab-out-of-bounds Read in bpf_clone_redirect	C		5	183d	409d	0/1	public: reported C repro on 2019/04/12 00:01

Sample crash report:

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
audit: type=1400 audit(1574356902.100:36): avc:  denied  { map } for  pid=6929 comm="syz-executor283" path="/root/syz-executor283383355" dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
==================================================================
BUG: KASAN: slab-out-of-bounds in ____bpf_clone_redirect net/core/filter.c:1768 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_clone_redirect+0x2de/0x2f0 net/core/filter.c:1759
Read of size 8 at addr ffff88809e0c2c10 by task syz-executor283/6929

CPU: 0 PID: 6929 Comm: syz-executor283 Not tainted 4.14.155-syzkaller #0
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+0x142/0x197 lib/dump_stack.c:58
 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
 ____bpf_clone_redirect net/core/filter.c:1768 [inline]
 bpf_clone_redirect+0x2de/0x2f0 net/core/filter.c:1759
 bpf_prog_3c8dfff8b3098609+0x3b0/0x1000

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff88809e0c2b80
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 144 bytes inside of
 232-byte region [ffff88809e0c2b80, ffff88809e0c2c68)
The buggy address belongs to the page:
page:ffffea0002783080 count:1 mapcount:0 mapping:ffff88809e0c2040 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff88809e0c2040 0000000000000000 000000010000000c
raw: ffffea00024b78a0 ffff8880a9e1bf48 ffff8880a9e19a80 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809e0c2b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809e0c2b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809e0c2c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88809e0c2c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809e0c2d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (11):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci2-linux-4-14	2019/11/21 17:24	linux-4.14.y	f56f3d0e	8098ea0f	.config	log	report	syz	C	ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/11/01 14:05	linux-4.14.y	ddef1e8e	a41ca8fa	.config	log	report	syz	C	ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/10/25 06:47	linux-4.14.y	b98aebd2	d01bb02a	.config	log	report	syz	C	ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/08/30 23:38	linux-4.14.y	01fd1694	9adfa876	.config	log	report	syz	C	ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/08/28 18:07	linux-4.14.y	b5260801	1eb076e9	.config	log	report	syz	C	ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/08/17 04:17	linux-4.14.y	45f092f9	8fd428a1	.config	log	report	syz	C	ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/07/19 12:26	linux-4.14.y	aea8526e	8304907d	.config	log	report	syz	C
ci2-linux-4-14	2019/12/29 05:34	linux-4.14.y	e1f7d50a	af6b8ef8	.config	log	report			ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/09/28 23:39	linux-4.14.y	f6e27dbb	eb6b9855	.config	log	report			ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/08/06 23:13	linux-4.14.y	b19ffe6e	da562c0b	.config	log	report			ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
ci2-linux-4-14	2019/07/19 12:05	linux-4.14.y	aea8526e	8304907d	.config	log	report