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Re: [tipc-discussion] KASAN: use-after-free Read in tipc_group_size
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From: Jon M. <jon...@er...> - 2018-01-08 20:11:50
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> -----Original Message----- > From: Cong Wang [mailto:xiy...@gm...] > Sent: Monday, January 08, 2018 13:44 > To: syzbot <syz...@sy...> > Cc: David Miller <da...@da...>; Jon Maloy > <jon...@er...>; LKML <lin...@vg...>; Linux > Kernel Network Developers <ne...@vg...>; syzkaller- > bu...@go...; tip...@li...; Ying Xue > <yin...@wi...> > Subject: Re: KASAN: use-after-free Read in tipc_group_size > > On Mon, Jan 8, 2018 at 6:58 AM, syzbot > <syz...@sy...> wrote: > > Hello, > > > > syzkaller hit the following crash on > > b2cd1df66037e7c4697c7e40496bf7e4a5e16a2d > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.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: syz...@sy... > > 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_size+0x40/0x50 > > net/tipc/group.c:158 Read of size 2 at addr ffff8801c08ba280 by task > > syzkaller447710/3513 > > > > CPU: 0 PID: 3513 Comm: syzkaller447710 Not tainted 4.15.0-rc7+ #252 > > 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_load2_noabort+0x14/0x20 mm/kasan/report.c:428 > > tipc_group_size+0x40/0x50 net/tipc/group.c:158 > > tipc_poll+0x374/0x4f0 net/tipc/socket.c:739 > > Seems we have to lock the sock for tipc_group_size() in tipc_poll(). Not quite. I think it is that we initialize 'grp' on the stack before we call sock_poll_wait() and access it after it returns. This is anyway fixed in patch #9 of the series I just sent to net-next, where the poll() handling for group members is redesigned. ///jon > > > > sock_poll+0x141/0x320 net/socket.c:1117 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: 0033:0x445cb9 > > RSP: 002b:00007f04886b1ce8 EFLAGS: 00000246 ORIG_RAX: > 0000000000000007 > > RAX: ffffffffffffffda RBX: 00000000006dac3c RCX: 0000000000445cb9 > > RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000020fa2ff8 > > RBP: 00000000006dac38 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > > R13: 00007ffc84d56d7f R14: 00007f04886b29c0 R15: 0000000000000005 > > > > Allocated by task 3510: > > 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+0x116/0x9c0 net/tipc/group.c:167 tipc_sk_join > > net/tipc/socket.c:2747 [inline] > > tipc_setsockopt+0x249/0xc10 net/tipc/socket.c:2861 SYSC_setsockopt > > net/socket.c:1829 [inline] > > SyS_setsockopt+0x189/0x360 net/socket.c:1808 > > entry_SYSCALL_64_fastpath+0x23/0x9a > > > > Freed by task 3510: > > 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:206 tipc_sk_join > > net/tipc/socket.c:2760 [inline] > > tipc_setsockopt+0xb0d/0xc10 net/tipc/socket.c:2861 SYSC_setsockopt > > net/socket.c:1829 [inline] > > SyS_setsockopt+0x189/0x360 net/socket.c:1808 > > entry_SYSCALL_64_fastpath+0x23/0x9a > > > > The buggy address belongs to the object at ffff8801c08ba200 which > > belongs to the cache kmalloc-192 of size 192 The buggy address is > > located 128 bytes inside of 192-byte region [ffff8801c08ba200, > > ffff8801c08ba2c0) The buggy address belongs to the page: > > page:ffffea0007022e80 count:1 mapcount:0 mapping:ffff8801c08ba000 > > index:0x0 > > flags: 0x2fffc0000000100(slab) > > raw: 02fffc0000000100 ffff8801c08ba000 0000000000000000 > > 0000000100000010 > > raw: ffffea00071338a0 ffffea0006fe2360 ffff8801dac00040 > > 0000000000000000 page dumped because: kasan: bad access detected > > > > Memory state around the buggy address: > > ffff8801c08ba180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > > ffff8801c08ba200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >> > >> ffff8801c08ba280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > > > > ^ > > ffff8801c08ba300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8801c08ba380: fb fb fb fb fb fb fb fb 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 syz...@go.... > > > > 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. |
