> -----Original Message----- > From: Cong Wang [mailto:xiyou.wangc...@gmail.com] > Sent: Monday, January 15, 2018 23:44 > To: syzbot <syzbot+799dafde028679585...@syzkaller.appspotmail.com> > Cc: David Miller <da...@davemloft.net>; Jon Maloy > <jon.ma...@ericsson.com>; LKML <linux-ker...@vger.kernel.org>; Linux > Kernel Network Developers <netdev@vger.kernel.org>; syzkaller- > b...@googlegroups.com; tipc-discuss...@lists.sourceforge.net; Ying Xue > <ying....@windriver.com> > Subject: Re: KASAN: use-after-free Read in tipc_group_is_open > > On Mon, Jan 15, 2018 at 7:58 PM, syzbot > <syzbot+799dafde028679585...@syzkaller.appspotmail.com> wrote: > > Hello, > > > > syzkaller hit the following crash on > > 594831a8aba3fd045c3212a3e3bb9788c77b989d > > git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/maste > > r > > 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 > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+799dafde028679585...@syzkaller.appspotmail.com > > It will help syzbot understand when the bug is fixed. See footer for > > details. > > If you forward the report, please keep this part and the footer. > > > > > ========================================================== > ======== > > BUG: KASAN: use-after-free in tipc_group_is_open+0x3a/0x40 > > net/tipc/group.c:106 > > Read of size 1 at addr ffff8801d89f7378 by task syzkaller275009/3704 > > > > CPU: 0 PID: 3704 Comm: syzkaller275009 Not tainted 4.15.0-rc7+ #190 > > 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_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_load1_noabort+0x14/0x20 mm/kasan/report.c:427 > > tipc_group_is_open+0x3a/0x40 net/tipc/group.c:106 > > tipc_poll+0x364/0x4d0 net/tipc/socket.c:740 > > > commit eb929a91b213d2a72c5a8b4af9a1acf63bfb8287 > Author: Jon Maloy <jon.ma...@ericsson.com> > Date: Mon Jan 8 21:03:31 2018 +0100 > > tipc: improve poll() for group member socket > > Apparently Jon's commit doesn't fix this. I also don't understand why Jon > believes sock_poll_wait() could sync with setsockopt path...
While sock_poll_wait() is sleeping, it is possible that the item the 'grp' stack variable is pointing to might be deleted, invalidating the pointer. This is why I moved the initialization of the pointer to after sock_poll_wait(). However, now tipc_sock->group is clearly set to NULL at both locations where a group item might be deleted, so the reason for the warning must be something else. I am open to suggestions. ///jon > > > > > sock_poll+0x141/0x320 net/socket.c:1111 do_pollfd fs/select.c:822 > > [inline] do_poll fs/select.c:872 [inline] > > do_sys_poll+0x715/0x10b0 fs/select.c:966 SYSC_poll fs/select.c:1024 > > [inline] > > SyS_poll+0x10d/0x450 fs/select.c:1012 > > entry_SYSCALL_64_fastpath+0x23/0x9a > > RIP: 0033:0x446129 > > RSP: 002b:00007f0f2df96db8 EFLAGS: 00000246 ORIG_RAX: > 0000000000000007 > > RAX: ffffffffffffffda RBX: 00000000006dbc54 RCX: 0000000000446129 > > RDX: 0000000000007fff RSI: 000000000000000a RDI: 0000000020ef5000 > > RBP: 00000000006dbc50 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > > R13: 00007ffc07e2923f R14: 00007f0f2df979c0 R15: 0000000000000007 > > > > Allocated by task 3702: > > 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 > > kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3610 kmalloc > > include/linux/slab.h:499 [inline] kzalloc include/linux/slab.h:688 > > [inline] > > tipc_group_create+0x144/0x900 net/tipc/group.c:180 tipc_sk_join > > net/tipc/socket.c:2762 [inline] > > tipc_setsockopt+0x274/0xce0 net/tipc/socket.c:2877 SYSC_setsockopt > > net/socket.c:1823 [inline] > > SyS_setsockopt+0x189/0x360 net/socket.c:1802 > > entry_SYSCALL_64_fastpath+0x23/0x9a > > > > Freed by task 3702: > > 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:3488 [inline] > > kfree+0xd6/0x260 mm/slab.c:3803 > > tipc_group_delete+0x2c8/0x3d0 net/tipc/group.c:234 tipc_sk_join > > net/tipc/socket.c:2775 [inline] > > tipc_setsockopt+0xaa9/0xce0 net/tipc/socket.c:2877 SYSC_setsockopt > > net/socket.c:1823 [inline] > > SyS_setsockopt+0x189/0x360 net/socket.c:1802 > > entry_SYSCALL_64_fastpath+0x23/0x9a > > > > The buggy address belongs to the object at ffff8801d89f7300 which > > belongs to the cache kmalloc-128 of size 128 The buggy address is > > located 120 bytes inside of 128-byte region [ffff8801d89f7300, > > ffff8801d89f7380) The buggy address belongs to the page: > > page:ffffea0007627dc0 count:1 mapcount:0 mapping:ffff8801d89f7000 > > index:0x0 > > flags: 0x2fffc0000000100(slab) > > raw: 02fffc0000000100 ffff8801d89f7000 0000000000000000 > > 0000000100000015 > > raw: ffffea0007622720 ffffea0007627ce0 ffff8801dac00640 > > 0000000000000000 page dumped because: kasan: bad access detected > > > > Memory state around the buggy address: > > ffff8801d89f7200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb > > ffff8801d89f7280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > >> > >> ffff8801d89f7300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > > > ^ > > ffff8801d89f7380: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 > > ffff8801d89f7400: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc > > > ========================================================== > ======== > > > > > > --- > > This bug is generated by a dumb bot. It may contain errors. > > See https://goo.gl/tpsmEJ for details. > > Direct all questions to syzkal...@googlegroups.com. > > > > syzbot will keep track of this bug report. > > If you forgot to add the Reported-by tag, once the fix for this bug is > > merged into any tree, please 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.
