WARNING in _copy_to_user

Hello,

syzkaller hit the following crash on df8ba95c572a187ed2aa7403e97a7a7f58c01f00
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

Unfortunately, I don't have any reproducer for this bug yet.



=====================================
WARNING: bad unlock balance detected!
4.15.0-rc1+ #202 Not tainted
-------------------------------------
syz-executor4/28722 is trying to release lock (mrt_lock) at:
[<00000000c358606b>] ipmr_mfc_seq_stop+0xe1/0x130 net/ipv6/ip6mr.c:553
but there are no more locks to release!

other info that might help us debug this:
2 locks held by syz-executor4/28722:
 #0:  (sb_writers#6){.+.+}, at: [<000000003332d098>] file_start_write include/linux/fs.h:2715 [inline]
 #0:  (sb_writers#6){.+.+}, at: [<000000003332d098>] do_sendfile+0xaec/0xe90 fs/read_write.c:1412
 #1:  (&p->lock){+.+.}, at: [<000000001572c807>] seq_read+0xd5/0x13d0 fs/seq_file.c:165

stack backtrace:
CPU: 0 PID: 28722 Comm: syz-executor4 Not tainted 4.15.0-rc1+ #202
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+0x194/0x257 lib/dump_stack.c:53
 print_unlock_imbalance_bug+0x12f/0x140 kernel/locking/lockdep.c:3561
 __lock_release kernel/locking/lockdep.c:3775 [inline]
 lock_release+0x5f9/0xda0 kernel/locking/lockdep.c:4023
 __raw_read_unlock include/linux/rwlock_api_smp.h:225 [inline]
 _raw_read_unlock+0x1a/0x30 kernel/locking/spinlock.c:255
 ipmr_mfc_seq_stop+0xe1/0x130 net/ipv6/ip6mr.c:553
 seq_read+0xc42/0x13d0 fs/seq_file.c:277
 proc_reg_read+0xef/0x170 fs/proc/inode.c:217

37 more lines

On Fri, Dec 01, 2017 at 03:30:01AM -0800, syzbot wrote:

Hello,

syzkaller hit the following crash on
df8ba95c572a187ed2aa7403e97a7a7f58c01f00
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

Unfortunately, I don't have any reproducer for this bug yet.



=====================================
WARNING: bad unlock balance detected!
4.15.0-rc1+ #202 Not tainted
-------------------------------------
syz-executor4/28722 is trying to release lock (mrt_lock) at:
[<00000000c358606b>] ipmr_mfc_seq_stop+0xe1/0x130 net/ipv6/ip6mr.c:553
but there are no more locks to release!

other info that might help us debug this:
2 locks held by syz-executor4/28722:
 #0:  (sb_writers#6){.+.+}, at: [<000000003332d098>] file_start_write
include/linux/fs.h:2715 [inline]
 #0:  (sb_writers#6){.+.+}, at: [<000000003332d098>] do_sendfile+0xaec/0xe90
fs/read_write.c:1412
 #1:  (&p->lock){+.+.}, at: [<000000001572c807>] seq_read+0xd5/0x13d0
fs/seq_file.c:165

stack backtrace:
CPU: 0 PID: 28722 Comm: syz-executor4 Not tainted 4.15.0-rc1+ #202
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+0x194/0x257 lib/dump_stack.c:53
 print_unlock_imbalance_bug+0x12f/0x140 kernel/locking/lockdep.c:3561
 __lock_release kernel/locking/lockdep.c:3775 [inline]
 lock_release+0x5f9/0xda0 kernel/locking/lockdep.c:4023

41 more quoted lines

Duplicate of "WARNING: bad unlock balance in ipmr_mfc_seq_stop" which syzbot is
detecting under that crash signature now, so just invalidating this one:

#syz invalid