WARNING in md_ioctl

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
c61a56ababa404961fa769a2b24229f18e461961 (Sun Apr 29 17:06:05 2018 +0000)
Merge branch 'x86-urgent-for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=1e46a0864c1a6e9bd3d8

C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5771999158730752
syzkaller reproducer:
https://syzkaller.appspot.com/x/repro.syz?id=6399853584187392
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=6389218171420672
Kernel config:
https://syzkaller.appspot.com/x/.config?id=4617060493481910265
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

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Reported-by: syzbot+1e46a0...@syzkaller.appspotmail.com
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random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
md: md0 stopped.
md: md0 stopped.
WARNING: CPU: 1 PID: 4511 at drivers/md/md.c:7188 md_ioctl+0x3427/0x6360
drivers/md/md.c:7188
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4511 Comm: syz-executor107 Not tainted 4.17.0-rc2+ #24
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+0x1b9/0x294 lib/dump_stack.c:113
panic+0x22f/0x4de kernel/panic.c:184
__warn.cold.8+0x163/0x1b3 kernel/panic.c:536
report_bug+0x252/0x2d0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:md_ioctl+0x3427/0x6360 drivers/md/md.c:7188
RSP: 0018:ffff8801ad9b7400 EFLAGS: 00010293
RAX: ffff8801acf7a540 RBX: 0000000000000932 RCX: ffffffff8565f354
RDX: 0000000000000000 RSI: ffffffff85661c37 RDI: 0000000000000007
RBP: ffff8801ad9b79c0 R08: ffff8801acf7a540 R09: ffffed0039894699
R10: ffff8801ad9b73f0 R11: ffff8801cc4a34cf R12: 0000000000000932
R13: ffff8801cc4a3328 R14: ffff8801ad9b7998 R15: 0000000000000001
__blkdev_driver_ioctl block/ioctl.c:303 [inline]
blkdev_ioctl+0x9b6/0x2020 block/ioctl.c:601
block_ioctl+0xee/0x130 fs/block_dev.c:1877
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
__do_sys_ioctl fs/ioctl.c:708 [inline]
__se_sys_ioctl fs/ioctl.c:706 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445a59
RSP: 002b:00007f00dd147da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445a59
RDX: 0000000020000080 RSI: 0000000000000932 RDI: 0000000000000003
RBP: 00000000006dac3c R08: 00007f00dd148700 R09: 0000000000000000
R10: 00007f00dd148700 R11: 0000000000000246 R12: 00000000006dac38
R13: 30646d2f7665642f R14: 00007f00dd1489c0 R15: 0000000000000003
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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[syzbot]

syzbot has bisected this bug to:

commit 4b6ce6810a5dc0af387a238e8c852e0d3822381f
Author: Rafael Antognolli <rafael.a...@intel.com>
Date: Mon Feb 5 23:33:30 2018 +0000

drm/i915/cnl: WaPipeControlBefore3DStateSamplePattern

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13aeb522e00000
start commit: c61a56ab Merge branch 'x86-urgent-for-linus' of git://git...
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=106eb522e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=17aeb522e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4013180e7c7a9ff9
dashboard link: https://syzkaller.appspot.com/bug?extid=1e46a0864c1a6e9bd3d8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16bca207800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14819a47800000

Reported-by: syzbot+1e46a0...@syzkaller.appspotmail.com
Fixes: 4b6ce6810a5d ("drm/i915/cnl:
WaPipeControlBefore3DStateSamplePattern")

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

[Daniel Vetter]

On Mon, Nov 25, 2019 at 02:37:01PM -0800, syzbot wrote:
> syzbot has bisected this bug to:
>
> commit 4b6ce6810a5dc0af387a238e8c852e0d3822381f
> Author: Rafael Antognolli <rafael.a...@intel.com>
> Date: Mon Feb 5 23:33:30 2018 +0000
>
> drm/i915/cnl: WaPipeControlBefore3DStateSamplePattern

This seems very unlikely, the reproducer doesn't open a drm device, and
I'd be surprised if your gcd instances have an actual i915 device in them
(but I can't check because boot log isn't provided, didn't find it on the
dashboard either).

Since i915 is built-in I suspect this simply moved something else in the
kernel image around which provokes the bug.
-Daniel

>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13aeb522e00000
> start commit: c61a56ab Merge branch 'x86-urgent-for-linus' of git://git...
> git tree: upstream
> final crash: https://syzkaller.appspot.com/x/report.txt?x=106eb522e00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=17aeb522e00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=4013180e7c7a9ff9
> dashboard link: https://syzkaller.appspot.com/bug?extid=1e46a0864c1a6e9bd3d8
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16bca207800000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14819a47800000
>
> Reported-by: syzbot+1e46a0...@syzkaller.appspotmail.com
> Fixes: 4b6ce6810a5d ("drm/i915/cnl:
> WaPipeControlBefore3DStateSamplePattern")
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

> _______________________________________________
> dri-devel mailing list
> dri-...@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch