On Sun, Dec 30, 2018 at 10:31 AM Dmitry Vyukov <dvyu...@google.com> wrote: > > On Wed, Dec 26, 2018 at 10:03 AM Dmitry Vyukov <dvyu...@google.com> wrote: > > > > Hello Dmitry, > > > > > > > > On 12/23/18 11:42 AM, Dmitry Vyukov wrote: > > > > > Actually was able to reproduce this with a syzkaller program: > > > > > ./syz-execprog -repeat=0 -procs=10 prog > > > > > ... > > > > > kasan: CONFIG_KASAN_INLINE enabled > > > > > kasan: GPF could be caused by NULL-ptr deref or user memory access > > > > > general protection fault: 0000 [#1] PREEMPT SMP KASAN > > > > > CPU: 1 PID: 8788 Comm: syz-executor8 Not tainted 4.20.0-rc7+ #6 > > > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 > > > > > 04/01/2014 > > > > > RIP: 0010:__list_del_entry_valid+0x7e/0x150 lib/list_debug.c:51 > > > > > Code: ad de 4c 8b 26 49 39 c4 74 66 48 b8 00 02 00 00 00 00 ad de 48 > > > > > 89 da 48 39 c3 74 65 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c > > > > > 02 00 75 7b 48 8b 13 48 39 f2 75 57 49 8d 7c 24 08 48 b8 00 > > > > > RSP: 0018:ffff88804faef210 EFLAGS: 00010a02 > > > > > RAX: dffffc0000000000 RBX: f817edba555e1f00 RCX: ffffffff831bad5f > > > > > RDX: 1f02fdb74aabc3e0 RSI: ffff88801b8a0720 RDI: ffff88801b8a0728 > > > > > RBP: ffff88804faef228 R08: fffff52001055401 R09: fffff52001055401 > > > > > R10: 0000000000000001 R11: fffff52001055400 R12: ffff88802d52cc98 > > > > > R13: ffff88801b8a0728 R14: ffff88801b8a0720 R15: dffffc0000000000 > > > > > FS: 0000000000d24940(0000) GS:ffff88802d500000(0000) > > > > > knlGS:0000000000000000 > > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > > CR2: 00000000004bb580 CR3: 0000000011177005 CR4: 00000000003606e0 > > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > > Call Trace: > > > > > __list_del_entry include/linux/list.h:117 [inline] > > > > > list_del include/linux/list.h:125 [inline] > > > > > unlink_queue ipc/sem.c:786 [inline] > > > > > freeary+0xddb/0x1c90 ipc/sem.c:1164 > > > > > free_ipcs+0xf0/0x160 ipc/namespace.c:112 > > > > > sem_exit_ns+0x20/0x40 ipc/sem.c:237 > > > > > free_ipc_ns ipc/namespace.c:120 [inline] > > > > > put_ipc_ns+0x55/0x160 ipc/namespace.c:152 > > > > > free_nsproxy+0xc0/0x1f0 kernel/nsproxy.c:180 > > > > > switch_task_namespaces+0xa5/0xc0 kernel/nsproxy.c:229 > > > > > exit_task_namespaces+0x17/0x20 kernel/nsproxy.c:234 > > > > > do_exit+0x19e5/0x27d0 kernel/exit.c:866 > > > > > do_group_exit+0x151/0x410 kernel/exit.c:970 > > > > > __do_sys_exit_group kernel/exit.c:981 [inline] > > > > > __se_sys_exit_group kernel/exit.c:979 [inline] > > > > > __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:979 > > > > > do_syscall_64+0x192/0x770 arch/x86/entry/common.c:290 > > > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > > RIP: 0033:0x4570e9 > > > > > Code: 5d af fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 > > > > > 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d > > > > > 01 f0 ff ff 0f 83 2b af fb ff c3 66 2e 0f 1f 84 00 00 00 00 > > > > > RSP: 002b:00007ffe35f12018 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > > > > > RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00000000004570e9 > > > > > RDX: 0000000000410540 RSI: 0000000000a34c00 RDI: 0000000000000045 > > > > > RBP: 00000000004a43a4 R08: 000000000000000c R09: 0000000000000000 > > > > > R10: 0000000000d24940 R11: 0000000000000246 R12: 0000000000000000 > > > > > R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000008 > > > > > Modules linked in: > > > > > Dumping ftrace buffer: > > > > > (ftrace buffer empty) > > > > > ---[ end trace 17829b0f00569a59 ]--- > > > > > RIP: 0010:__list_del_entry_valid+0x7e/0x150 lib/list_debug.c:51 > > > > > Code: ad de 4c 8b 26 49 39 c4 74 66 48 b8 00 02 00 00 00 00 ad de 48 > > > > > 89 da 48 39 c3 74 65 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c > > > > > 02 00 75 7b 48 8b 13 48 39 f2 75 57 49 8d 7c 24 08 48 b8 00 > > > > > RSP: 0018:ffff88804faef210 EFLAGS: 00010a02 > > > > > RAX: dffffc0000000000 RBX: f817edba555e1f00 RCX: ffffffff831bad5f > > > > > RDX: 1f02fdb74aabc3e0 RSI: ffff88801b8a0720 RDI: ffff88801b8a0728 > > > > > RBP: ffff88804faef228 R08: fffff52001055401 R09: fffff52001055401 > > > > > R10: 0000000000000001 R11: fffff52001055400 R12: ffff88802d52cc98 > > > > > R13: ffff88801b8a0728 R14: ffff88801b8a0720 R15: dffffc0000000000 > > > > > FS: 0000000000d24940(0000) GS:ffff88802d500000(0000) > > > > > knlGS:0000000000000000 > > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > > CR2: 00000000004bb580 CR3: 0000000011177005 CR4: 00000000003606e0 > > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > > > > > > > > > > > > The prog is: > > > > > unshare(0x8020000) > > > > > semget$private(0x0, 0x4007, 0x0) > > > > > > > > > > kernel is on 9105b8aa50c182371533fc97db64fc8f26f051b3 > > > > > > > > > > and again it involved lots of oom kills, the repro eats all memory, a > > > > > process getting killed, frees some memory and the process repeats. > > > > > > > > I was too fast: I can't reproduce the memory leak. > > > > > > > > Can you send me the source for prog? > > > > > > > > > Here is the program: > > > https://gist.githubusercontent.com/dvyukov/03ec54b3429ade16fa07bf8b2379aff3/raw/ae4f654e279810de2505e8fa41b73dc1d77778e6/gistfile1.txt > > > > > > But we concluded this is not a leak, right? > > > It just creates large semaphores tied to a persistent ipcns. Once the > > > process is killed, all memory is released. When this program runs, it > > > eats all memory, then one of the subprocesses is oom-killed, part of > > > memory is released, then all memory is consumed again by a new > > > subprocess and this repeats. If all processes are killed, all memory > > > is released back. It seems to be working as intended. > > > > > > However, what you said about kernel.sem sysctl is useful and I think > > > we need to use it for additional sandboxing of syzkaller test > > > processes. I am thinking of applying: > > > > > > kernel.shmmax = 16777216 > > > kernel.shmall = 536870912 > > > kernel.shmmni = 1024 > > > kernel.msgmax = 8192 > > > kernel.msgmni = 1024 > > > kernel.msgmnb = 1024 > > > kernel.sem = 1024 1048576 500 1024 > > > > > > It should be enough to trigger bugs of any complexity (oom's aside), > > > but should prevent uncontrolled memory consumption. > > > Looking at the code I figured that these sysctls are > > > per-ipc-namespace, right? I.e. if I do sysctl from an ipcns, the > > > limits will be set only only for that ns. I won't use this initially, > > > but something to keep in mind if the global limits will fail in some > > > way. > > > > +Shakeel who was interested in memory isolation problems > > > > Setting these sysctl's globally does not help, as they are reset for > > new ipc namespaces (?). Setting them for test process namespaces does > > not help either, as it's trivial to do unshare(NEWIPC) (which the > > repro in fact does). It seems to make things somewhat better for > > syzkaller because any namespaces that a test creates are short-lived. > > But this seems to be a general resource isolation issue for > > containers. > > > The stack overflow was reported 5 months ago with a bunch of repros: > https://groups.google.com/forum/#!msg/syzkaller-bugs/C7d0Hm6YcDM/nQeciKgtCgAJ > now we are spending time re-debugging other incarnations of the same bug.
FTR, the main place to track the stack overflow is now this thread: https://groups.google.com/forum/#!msg/syzkaller-bugs/nFeC8-UG1gg/_KMuN0ViFQAJ Manfred, you are proceeding with submission of the race fix, right? Since it includes 3 Reported-by tags I will not mark these bugs as dup of "kernel panic: corrupted stack end in wb_workfn", otherwise it will cause confusion (the patch will appear as fixing the stack overflow which it is not). Of, if you remove the tags, we can mark these 3 bugs as a dup.
