From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753859AbeAaAa2 (ORCPT ); Tue, 30 Jan 2018 19:30:28 -0500 Received: from mail-it0-f46.google.com ([209.85.214.46]:38424 "EHLO mail-it0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751429AbeAaAa0 (ORCPT ); Tue, 30 Jan 2018 19:30:26 -0500 X-Google-Smtp-Source: AH8x224p1nBYIOR7XN1eCywNe9TblpOxvCSIyZpdYlu6T9H6VoAl1lmo5NtAZWScnCX4CIJ3Nsk+/w== Date: Tue, 30 Jan 2018 16:30:22 -0800 From: Eric Biggers To: syzbot Cc: davem@davemloft.net, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, yoshfuji@linux-ipv6.org Subject: Re: WARNING: bad unlock balance in ipmr_mfc_seq_stop Message-ID: <20180131003022.o7qo3eftbjj4qcbk@gmail.com> References: <001a1144a1ee7405cb0560706451@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <001a1144a1ee7405cb0560706451@google.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 15, 2017 at 11:52:01PM -0800, syzbot wrote: > Hello, > > syzkaller hit the following crash on > a638349bf6c29433b938141f99225b160551ff48 > 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. > C reproducer is attached > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > for information about syzkaller reproducers > > > > ===================================== > WARNING: bad unlock balance detected! > 4.15.0-rc3+ #128 Not tainted > ------------------------------------- > syzkaller971460/3195 is trying to release lock (mrt_lock) at: > [<000000006898068d>] 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: > 1 lock held by syzkaller971460/3195: > #0: (&p->lock){+.+.}, at: [<00000000744a6565>] seq_read+0xd5/0x13d0 > fs/seq_file.c:165 > > stack backtrace: > CPU: 1 PID: 3195 Comm: syzkaller971460 Not tainted 4.15.0-rc3+ #128 > 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 > traverse+0x3bc/0xa00 fs/seq_file.c:135 > seq_read+0x96a/0x13d0 fs/seq_file.c:189 > proc_reg_read+0xef/0x170 fs/proc/inode.c:217 > do_loop_readv_writev fs/read_write.c:673 [inline] > do_iter_read+0x3db/0x5b0 fs/read_write.c:897 > compat_readv+0x1bf/0x270 fs/read_write.c:1140 > do_compat_preadv64+0xdc/0x100 fs/read_write.c:1189 > C_SYSC_preadv fs/read_write.c:1209 [inline] > compat_SyS_preadv+0x3b/0x50 fs/read_write.c:1203 > do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] > do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 > entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 > RIP: 0023:0xf7f73c79 > RSP: 002b:00000000e574a15c EFLAGS: 00000292 ORIG_RAX: 000000000000014d > RAX: ffffffffffffffda RBX: 000000000000000f RCX: 0000000020a3afb0 > RDX: 0000000000000001 RSI: 0000000000000067 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > BUG: sleeping function called from invalid context at lib/usercopy.c:25 > in_atomic(): 1, irqs_disabled(): 0, pid: 3195, name: syzkaller971460 > INFO: lockdep is turned off. > CPU: 1 PID: 3195 Comm: syzkaller971460 Not tainted 4.15.0-rc3+ #128 > 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 > ___might_sleep+0x2b2/0x470 kernel/sched/core.c:6060 > __might_sleep+0x95/0x190 kernel/sched/core.c:6013 > __might_fault+0xab/0x1d0 mm/memory.c:4525 > _copy_to_user+0x2c/0xc0 lib/usercopy.c:25 > copy_to_user include/linux/uaccess.h:155 [inline] > seq_read+0xcb4/0x13d0 fs/seq_file.c:279 > proc_reg_read+0xef/0x170 fs/proc/inode.c:217 > do_loop_readv_writev fs/read_write.c:673 [inline] > do_iter_read+0x3db/0x5b0 fs/read_write.c:897 > compat_readv+0x1bf/0x270 fs/read_write.c:1140 > do_compat_preadv64+0xdc/0x100 fs/read_write.c:1189 > C_SYSC_preadv fs/read_write.c:1209 [inline] > compat_SyS_preadv+0x3b/0x50 fs/read_write.c:1203 > do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] > do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 > entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125 > RIP: 0023:0xf7f73c79 > RSP: 002b:00000000e574a15c EFLAGS: 00000292 ORIG_RAX: 000000000000014d > RAX: ffffffffffffffda RBX: 000000000000000f RCX: 0000000020a3afb0 > RDX: 0000000000000001 RSI: 0000000000000067 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > WARNING: CPU: 1 PID: 3195 at lib/usercopy.c:26 _copy_to_user+0xb5/0xc0 > lib/usercopy.c:26 > > > --- > This bug is generated by a dumb bot. It may contain errors. > See https://goo.gl/tpsmEJ for details. > Direct all questions to syzkaller@googlegroups.com. > Please credit me with: Reported-by: syzbot > > syzbot will keep track of this bug report. > Once a fix for this bug is merged into any tree, reply to this email with: > #syz fix: exact-commit-title > If you want to test a patch for this bug, please reply with: > #syz test: git://repo/address.git branch > and provide the patch inline or as an attachment. > To mark this as a duplicate of another syzbot report, please reply with: > #syz dup: exact-subject-of-another-report > If it's a one-off invalid bug report, please reply with: > #syz invalid > Note: if the crash happens again, it will cause creation of a new bug > report. > Note: all commands must start from beginning of the line in the email body. This is still happening. Here's a simplified reproducer, assuming that CONFIG_IPV6_MROUTE and CONFIG_PROVE_LOCKING are enabled: #include #include #include #include #include int main() { struct mf6cctl ctl = { }; int cachefd = open("/proc/self/net/ip6_mr_cache", O_RDONLY); int sockfd = socket(AF_INET6, SOCK_RAW, 0x3aul); char buf[2]; if (fork() == 0) { for (;;) pread(cachefd, buf, 2, 103); } else { for (;;) { setsockopt(sockfd, SOL_IPV6, MRT6_ADD_MFC, &ctl, sizeof(ctl)); } } }