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Date:   Wed, 21 Aug 2019 06:37:00 -0700
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Message-ID: <000000000000ed58060590a0aa30@google.com>
Subject: Re: KASAN: slab-out-of-bounds Read in hidraw_ioctl
From:   syzbot <syzbot+5a6c4ec678a0c6ee84ba@syzkaller.appspotmail.com>
To:     andreyknvl@google.com, benjamin.tissoires@redhat.com,
        jikos@kernel.org, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
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Sender: linux-kernel-owner@vger.kernel.org
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Hello,

syzbot has tested the proposed patch but the reproducer still triggered  
crash:
KASAN: slab-out-of-bounds Read in hidraw_ioctl

==================================================================
BUG: KASAN: slab-out-of-bounds in strlen+0x79/0x90 lib/string.c:525
Read of size 1 at addr ffff8881c8035f38 by task syz-executor.4/2833

CPU: 1 PID: 2833 Comm: syz-executor.4 Not tainted 5.3.0-rc2+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0xca/0x13e lib/dump_stack.c:113
  print_address_description+0x6a/0x32c mm/kasan/report.c:351
  __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482
  kasan_report+0xe/0x12 mm/kasan/common.c:612
  strlen+0x79/0x90 lib/string.c:525
  strlen include/linux/string.h:281 [inline]
  hidraw_ioctl+0x245/0xae0 drivers/hid/hidraw.c:446
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:509 [inline]
  do_vfs_ioctl+0xd2d/0x1330 fs/ioctl.c:696
  ksys_ioctl+0x9b/0xc0 fs/ioctl.c:713
  __do_sys_ioctl fs/ioctl.c:720 [inline]
  __se_sys_ioctl fs/ioctl.c:718 [inline]
  __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:718
  do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7a68f6dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829
RDX: 0000000000000000 RSI: 0000000080404805 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7a68f6e6d4
R13: 00000000004c21de R14: 00000000004d5620 R15: 00000000ffffffff

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8881c8035e60
  which belongs to the cache shmem_inode_cache of size 1168
The buggy address is located 216 bytes inside of
  1168-byte region [ffff8881c8035e60, ffff8881c80362f0)
The buggy address belongs to the page:
page:ffffea0007200d00 refcount:1 mapcount:0 mapping:ffff8881da115180  
index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da115180
raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881c8035e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8881c8035e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8881c8035f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                         ^
  ffff8881c8035f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8881c8036000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         e96407b4 usb-fuzzer: main usb gadget fuzzer driver
git tree:       https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=14f14a1e600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cfa2c18fb6a8068e
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
patch:          https://syzkaller.appspot.com/x/patch.diff?x=171cd95a600000