syzbot


KASAN: use-after-free Read in bpf_test_finish

Status: upstream: reported C repro on 2019/08/03 11:31
Reported-by: syzbot+3c9ad1804804b4de0fae@syzkaller.appspotmail.com
First crash: 1781d, last: 1477d
Fix bisection the fix commit could be any of (bisect log):
  10d6aa565d05 Linux 4.14.135
  4139fb08c05f Linux 4.14.187
  
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in bpf_test_finish bpf net C 1211 2157d 2171d 8/27 fixed on 2018/08/07 13:43
android-414 KASAN: use-after-free Read in bpf_test_finish C 388 1750d 1895d 0/1 public: reported C repro on 2019/04/11 00:00
Last patch testing requests (2)
Created Duration User Patch Repo Result
2023/01/19 23:32 10m retest repro linux-4.14.y report log
2022/09/04 13:27 15m retest repro linux-4.14.y report log
Fix bisection attempts (8)
Created Duration User Patch Repo Result
2020/07/02 02:55 29m (2) bisect fix linux-4.14.y job log (2)
2020/06/02 02:31 23m bisect fix linux-4.14.y job log (0) log
2020/05/03 02:06 25m bisect fix linux-4.14.y job log (0) log
2020/04/02 22:37 23m bisect fix linux-4.14.y job log (0) log
2020/03/03 22:05 27m bisect fix linux-4.14.y job log (0) log
2020/02/02 20:31 24m bisect fix linux-4.14.y job log (0) log
2020/01/03 18:39 24m bisect fix linux-4.14.y job log (0) log
2019/12/04 18:16 23m bisect fix linux-4.14.y job log (0) log

Sample crash report:
audit: type=1400 audit(1564829577.213:36): avc:  denied  { map } for  pid=6952 comm="syz-executor429" path="/root/syz-executor429329191" dev="sda1" ino=16483 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: use-after-free in _copy_to_user+0xa4/0xd0 lib/usercopy.c:27
Read of size 924 at addr ffff8880747ffff3 by task syz-executor429/6952

CPU: 0 PID: 6952 Comm: syz-executor429 Not tainted 4.14.135 #31
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+0x138/0x19c 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
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x123/0x190 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 _copy_to_user+0xa4/0xd0 lib/usercopy.c:27
 copy_to_user include/linux/uaccess.h:155 [inline]
 bpf_test_finish.isra.0+0xaf/0x150 net/bpf/test_run.c:59
 bpf_prog_test_run_skb+0x5af/0x9a0 net/bpf/test_run.c:144
 bpf_prog_test_run kernel/bpf/syscall.c:1258 [inline]
 SYSC_bpf kernel/bpf/syscall.c:1520 [inline]
 SyS_bpf+0x749/0x38f3 kernel/bpf/syscall.c:1469
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x440379
RSP: 002b:00007ffd82ee9fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440379
RDX: 0000000000000028 RSI: 0000000020000140 RDI: 000000000000000a
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401c00
R13: 0000000000401c90 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0001d1ffc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffffea0001d1ffe0 ffffea0001d1ffe0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880747ffe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880747fff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880747fff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff888074800000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888074800080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/08/03 11:06 linux-4.14.y 10d6aa565d05 6affd8e8 .config console log report syz C ci2-linux-4-14
2019/08/30 14:46 linux-4.14.y 01fd1694b93c 9adfa876 .config console log report ci2-linux-4-14
2019/08/17 10:47 linux-4.14.y 45f092f9e9cb 8fd428a1 .config console log report ci2-linux-4-14
2019/08/03 10:30 linux-4.14.y 10d6aa565d05 6affd8e8 .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.