From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: Re: KASAN: use-after-free Read in inet_create Date: Sun, 8 Apr 2018 16:17:56 -0700 Message-ID: <20180408231756.GI685@sol.localdomain> References: <001a1144d1c8e819f6055fee7118@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: syzbot , 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 To: linux-rdma@vger.kernel.org, rds-devel@oss.oracle.com, Santosh Shilimkar Return-path: Content-Disposition: inline In-Reply-To: <001a1144d1c8e819f6055fee7118@google.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org [+RDS list and maintainer] On Sat, Dec 09, 2017 at 12:50:01PM -0800, syzbot wrote: > Hello, > > syzkaller hit the following crash on > 82bcf1def3b5f1251177ad47c44f7e17af039b4b > git://git.cmpxchg.org/linux-mmots.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. > > > ================================================================== > BUG: KASAN: use-after-free in inet_create+0xda0/0xf50 net/ipv4/af_inet.c:338 > Read of size 4 at addr ffff8801bde28554 by task kworker/u4:5/3492 > > CPU: 0 PID: 3492 Comm: kworker/u4:5 Not tainted 4.15.0-rc2-mm1+ #39 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Workqueue: krdsd rds_connect_worker > Call Trace: > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:53 > print_address_description+0x73/0x250 mm/kasan/report.c:252 > kasan_report_error mm/kasan/report.c:351 [inline] > kasan_report+0x25b/0x340 mm/kasan/report.c:409 > __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 > inet_create+0xda0/0xf50 net/ipv4/af_inet.c:338 > __sock_create+0x4d4/0x850 net/socket.c:1265 > sock_create_kern+0x3f/0x50 net/socket.c:1311 > rds_tcp_conn_path_connect+0x26f/0x920 net/rds/tcp_connect.c:108 > rds_connect_worker+0x156/0x1f0 net/rds/threads.c:165 > process_one_work+0xbfd/0x1bc0 kernel/workqueue.c:2113 > worker_thread+0x223/0x1990 kernel/workqueue.c:2247 > kthread+0x37a/0x440 kernel/kthread.c:238 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 > > Allocated by task 3362: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 > kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 > kmem_cache_alloc+0x12e/0x760 mm/slab.c:3548 > kmem_cache_zalloc include/linux/slab.h:695 [inline] > net_alloc net/core/net_namespace.c:362 [inline] > copy_net_ns+0x196/0x580 net/core/net_namespace.c:402 > create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107 > unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206 > SYSC_unshare kernel/fork.c:2421 [inline] > SyS_unshare+0x653/0xfa0 kernel/fork.c:2371 > entry_SYSCALL_64_fastpath+0x1f/0x96 > > Freed by task 35: > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > set_track mm/kasan/kasan.c:459 [inline] > kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 > __cache_free mm/slab.c:3492 [inline] > kmem_cache_free+0x77/0x280 mm/slab.c:3750 > net_free+0xca/0x110 net/core/net_namespace.c:378 > net_drop_ns.part.11+0x26/0x30 net/core/net_namespace.c:385 > net_drop_ns net/core/net_namespace.c:384 [inline] > cleanup_net+0x895/0xb60 net/core/net_namespace.c:502 > process_one_work+0xbfd/0x1bc0 kernel/workqueue.c:2113 > worker_thread+0x223/0x1990 kernel/workqueue.c:2247 > kthread+0x37a/0x440 kernel/kthread.c:238 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 > > The buggy address belongs to the object at ffff8801bde28080 > which belongs to the cache net_namespace of size 6272 > The buggy address is located 1236 bytes inside of > 6272-byte region [ffff8801bde28080, ffff8801bde29900) > The buggy address belongs to the page: > page:00000000df6a4dc0 count:1 mapcount:0 mapping:00000000553659f1 index:0x0 > compound_mapcount: 0 > flags: 0x2fffc0000008100(slab|head) > raw: 02fffc0000008100 ffff8801bde28080 0000000000000000 0000000100000001 > raw: ffffea0006f75da0 ffffea0006f60220 ffff8801d989fe00 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801bde28400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801bde28480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8801bde28500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff8801bde28580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801bde28600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > 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 > 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 regularly, though syzbot hasn't been able to generate a reproducer yet. All the reports seem to involve rds_connect_worker() encountering a freed network namespace (struct net) when calling sock_create_kern() from rds_tcp_conn_path_connect(). Probably something in RDS needs to be taking a reference to the network namespace and isn't, or the RDS workqueue isn't being shut down correctly. You can see all reports of this on the syzbot dashboard at https://syzkaller.appspot.com/bug?id=1f45ae538a0453220337ccb84962249fdd67107f. Last one was April 5 on Linus' tree (commit 3e968c9f1401088). - Eric