kernel BUG at drivers/android/binder_alloc.c:LINE! (3)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 1a9df9e2 Merge git://git.kernel.org/pub/scm/linux/kernel/g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11fed11f200000
kernel config: https://syzkaller.appspot.com/x/.config?x=8dcdce25ea72bedf
dashboard link: https://syzkaller.appspot.com/bug?extid=f9f3f388440283da2965
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17d05637200000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1677e62f200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f9f3f3...@syzkaller.appspotmail.com

binder: 7824:7824 DecRefs 0 refcount change on invalid ref 1 ret -22
------------[ cut here ]------------
kernel BUG at drivers/android/binder_alloc.c:1141!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7824 Comm: syz-executor570 Not tainted 5.1.0-rc2+ #40
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:binder_alloc_do_buffer_copy+0xd6/0x510
drivers/android/binder_alloc.c:1141
Code: 02 00 0f 85 20 04 00 00 4d 8b 64 24 58 49 29 dc e8 4f f4 23 fc 4c 89
e6 4c 89 ef e8 64 f5 23 fc 4d 39 e5 76 07 e8 3a f4 23 fc <0f> 0b e8 33 f4
23 fc 4c 8b 75 d0 4d 29 ec 4c 89 e6 4c 89 f7 e8 41
RSP: 0018:ffff88808b497550 EFLAGS: 00010293
RAX: ffff88808620e540 RBX: 0000000020001000 RCX: ffffffff854c7d3c
RDX: 0000000000000000 RSI: ffffffff854c7d46 RDI: 0000000000000006
RBP: ffff88808b4975d0 R08: ffff88808620e540 R09: 0000000000000028
R10: ffffed1011692f01 R11: ffff88808b49780f R12: 0000000000000008
R13: 0000000000000028 R14: ffff888088a0cb10 R15: 0000000000000000
FS: 00000000006de940(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004c4d28 CR3: 0000000090d8e000 CR4: 00000000001406e0
Call Trace:
binder_alloc_copy_from_buffer+0x37/0x42 drivers/android/binder_alloc.c:1187
binder_get_object+0xc3/0x200 drivers/android/binder.c:2062
binder_transaction+0x2b4a/0x6690 drivers/android/binder.c:3231
binder_thread_write+0x87e/0x2820 drivers/android/binder.c:3781
binder_ioctl_write_read drivers/android/binder.c:4825 [inline]
binder_ioctl+0x1033/0x183b drivers/android/binder.c:5002
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445f19
Code: e8 7c e7 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 db cb fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffeaa7b578 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000445f19
RDX: 0000000020000240 RSI: 00000000c0306201 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000403010
R10: 00007fffeaa7b0d0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000403010 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 0f3d90ce4ca56ff6 ]---
RIP: 0010:binder_alloc_do_buffer_copy+0xd6/0x510
drivers/android/binder_alloc.c:1141
Code: 02 00 0f 85 20 04 00 00 4d 8b 64 24 58 49 29 dc e8 4f f4 23 fc 4c 89
e6 4c 89 ef e8 64 f5 23 fc 4d 39 e5 76 07 e8 3a f4 23 fc <0f> 0b e8 33 f4
23 fc 4c 8b 75 d0 4d 29 ec 4c 89 e6 4c 89 f7 e8 41
RSP: 0018:ffff88808b497550 EFLAGS: 00010293
RAX: ffff88808620e540 RBX: 0000000020001000 RCX: ffffffff854c7d3c
RDX: 0000000000000000 RSI: ffffffff854c7d46 RDI: 0000000000000006
RBP: ffff88808b4975d0 R08: ffff88808620e540 R09: 0000000000000028
R10: ffffed1011692f01 R11: ffff88808b49780f R12: 0000000000000008
R13: 0000000000000028 R14: ffff888088a0cb10 R15: 0000000000000000
FS: 00000000006de940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004c4d28 CR3: 0000000090d8e000 CR4: 00000000001406f0


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
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syzbot can test patches for this bug, for details see:
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[Todd Kjos]

The fix for this is in Greg KH's char-misc-linus branch. Pointing
syzbot at it to verify:

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
char-misc-linus

[syzbot]

Hello,

syzbot tried to test the proposed patch but build/boot failed:

patch is already applied


Tested on:

commit: 0532a1b0 virt: vbox: Implement passing requestor info to t..
git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
char-misc-linus

compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=1577678b200000

[Todd Kjos]

Trying again without (redundantly) attaching the patch...

[syzbot]

syzbot has bisected this bug to:

commit 1a7c3d9bb7a926e88d5f57643e75ad1abfc55013
Author: Todd Kjos <tk...@android.com>
Date: Fri Feb 8 18:35:14 2019 +0000

binder: create userspace-to-binder-buffer copy function

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15b9383f200000
start commit: 1a9df9e2 Merge git://git.kernel.org/pub/scm/linux/kernel/g..
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=17b9383f200000
console output: https://syzkaller.appspot.com/x/log.txt?x=13b9383f200000

kernel config: https://syzkaller.appspot.com/x/.config?x=8dcdce25ea72bedf
dashboard link: https://syzkaller.appspot.com/bug?extid=f9f3f388440283da2965

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17d05637200000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1677e62f200000

Reported-by: syzbot+f9f3f3...@syzkaller.appspotmail.com
Fixes: 1a7c3d9bb7a9 ("binder: create userspace-to-binder-buffer copy
function")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

Hello,

syzbot tried to test the proposed patch but build/boot failed:

timed out

Tested on:

commit: 0532a1b0 virt: vbox: Implement passing requestor info to t..
git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
char-misc-linus

kernel config: https://syzkaller.appspot.com/x/.config?x=8dcdce25ea72bedf

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
syzbot+f9f3f3...@syzkaller.appspotmail.com

Tested on:

commit: 8c2ffd91 Linux 5.1-rc2
git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git master

kernel config: https://syzkaller.appspot.com/x/.config?x=8dcdce25ea72bedf
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=167ed663200000

Note: testing is done by a robot and is best-effort only.

[Todd Kjos]

Sigh. One more try... master with the same patch as an attachment.
(the patch is already queued up in gregkh's 'char-misc-linus' branch).

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
master

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
syzbot+f9f3f3...@syzkaller.appspotmail.com

Tested on:

commit: 8c2ffd91 Linux 5.1-rc2
git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git master

kernel config: https://syzkaller.appspot.com/x/.config?x=8dcdce25ea72bedf
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=10fed663200000

[Dmitry Vyukov]

Todd,

Should this patch fix the bug? Should we close the bug as fixed then?
In my local testing I see this BUG still fires, but if we will leave
old fixed bugs open, we will not get notifications about new crashes.

[Todd Kjos]

Yes (and syzbot seemed to confirm the fix). I didn't realize I needed
to manually close the issue. I guess you closed it yesterday.

[Dmitry Vyukov]

On Fri, May 17, 2019 at 5:26 PM Todd Kjos <tk...@google.com> wrote:
>
> Yes (and syzbot seemed to confirm the fix). I didn't realize I needed
> to manually close the issue. I guess you closed it yesterday.

This is required to auto-close the bug when the commit is merged:

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+f9f3f3...@syzkaller.appspotmail.com

Otherwise somebody needs to say:

#syz fix: binder: fix BUG_ON found by selinux-testsuite

[Todd Kjos]

[Todd Kjos]

On Fri, May 17, 2019 at 8:33 AM Dmitry Vyukov <dvy...@google.com> wrote:
>

> On Fri, May 17, 2019 at 5:26 PM Todd Kjos <tk...@google.com> wrote:
> >
> > Yes (and syzbot seemed to confirm the fix). I didn't realize I needed
> > to manually close the issue. I guess you closed it yesterday.
>
> This is required to auto-close the bug when the commit is merged:
>
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+f9f3f3...@syzkaller.appspotmail.com
>
> Otherwise somebody needs to say:
>
> #syz fix: binder: fix BUG_ON found by selinux-testsuite

It looks like you closed it with your #sys comment ^^^