On Fri, Dec 14, 2018 at 1:51 PM syzbot <syzbot+7713f3aa67be76b1552c@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: f5d582777bcb Merge branch 'for-linus' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=16aca143400000 > kernel config: https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23 > dashboard link: https://syzkaller.appspot.com/bug?extid=7713f3aa67be76b1552c > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1131381b400000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13bae593400000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+7713f3aa67be76b1552c@xxxxxxxxxxxxxxxxxxxxxxxxx +linux-mm for memcg question What the repro does is effectively just setsockopt(EBT_SO_SET_ENTRIES). This eats all machine memory and causes OOMs. Somehow it also caused the GPF in watchdog when it iterates over task list, perhaps some scheduler code leaves a dangling pointer on OOM failures. But what bothers me is a different thing. syzkaller test processes are sandboxed with a restrictive memcg which should prevent them from eating all memory. do_replace_finish calls vmalloc, which uses GFP_KERNEL, which does not include GFP_ACCOUNT (GFP_KERNEL_ACCOUNT does). And page alloc seems to change memory against memcg iff GFP_ACCOUNT is provided. Am I missing something or vmalloc is indeed not accounted (DoS)? I see some explicit uses of GFP_KERNEL_ACCOUNT, e.g. the one below, but they seem to be very sparse. static void *seq_buf_alloc(unsigned long size) { return kvmalloc(size, GFP_KERNEL_ACCOUNT); } Now looking at the code I also don't see how kmalloc(GFP_KERNEL) is accounted... Which makes me think I am still missing something. > Node 0 DMA free:15908kB min:164kB low:204kB high:244kB active_anon:0kB > inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB > writepending:0kB present:15992kB managed:15908kB mlocked:0kB > kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB > free_cma:0kB > 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: 1019 Comm: khungtaskd Not tainted 4.20.0-rc6+ #150 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline] > RIP: 0010:watchdog+0x492/0x1060 kernel/hung_task.c:289 > Code: 44 89 b5 30 fe ff ff 48 c1 e8 03 4c 01 e8 48 89 85 e8 fd ff ff e9 f8 > 00 00 00 e8 29 f3 ff ff 48 8d 7b 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 > 0f 85 70 0a 00 00 4c 8b 73 10 bf 02 00 00 00 4c 89 > RSP: 0018:ffff8881d7b37cc8 EFLAGS: 00010202 > RAX: 01a5bfffffffff51 RBX: 0d2dfffffffffa7a RCX: ffffffff817f9259 > RDX: 0000000000000000 RSI: ffffffff817f9147 RDI: 0d2dfffffffffa8a > xt_bpf: check failed: parse error > RBP: ffff8881d7b37f00 R08: ffff8881d7bae140 R09: ffffed103b5e5b5f > R10: ffffed103b5e5b5f R11: ffff8881daf2dafb R12: 00000000000003d6 > R13: dffffc0000000000 R14: 1ffff1103af66fbb R15: 00000000003fffd7 > FS: 0000000000000000(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f98b2d7c324 CR3: 00000001931bf000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > lowmem_reserve[]: 0 2818 6321 6321 > Node 0 DMA32 free:43812kB min:30052kB low:37564kB high:45076kB > active_anon:6236kB inactive_anon:0kB active_file:0kB inactive_file:80kB > unevictable:0kB writepending:0kB present:3129332kB managed:2888780kB > mlocked:0kB kernel_stack:32kB pagetables:0kB bounce:0kB free_pcp:200kB > local_pcp:200kB free_cma:0kB > kthread+0x35a/0x440 kernel/kthread.c:246 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 > Modules linked in: > lowmem_reserve[]: 0 0 3503 3503 > Node 0 Normal free:158644kB min:37364kB low:46704kB high:56044kB > active_anon:4768kB inactive_anon:768kB active_file:556kB > inactive_file:1936kB unevictable:0kB writepending:0kB present:4718592kB > managed:3587816kB mlocked:0kB kernel_stack:5952kB pagetables:1172kB > bounce:0kB free_pcp:2416kB local_pcp:604kB free_cma:0kB > lowmem_reserve[]: 0 0 0 0 > Node 0 DMA: 1*4kB (U) 0*8kB 0*16kB 1*32kB (U) 2*64kB (U) 1*128kB (U) > 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15908kB > Node 0 DMA32: 21*4kB (UM) 19*8kB (ME) 17*16kB (UM) 15*32kB (UME) 13*64kB > (ME) 4*128kB (M) 3*256kB (UM) 16*512kB (UM) 12*1024kB (UME) 6*2048kB (UME) > 2*4096kB (UM) = 44060kB > Node 0 Normal: 366*4kB (UME) 308*8kB (UME) 615*16kB (UME) 146*32kB (UME) > 467*64kB (UME) 43*128kB (UM) 4*256kB (UM) 2*512kB (ME) 2*1024kB (ME) > 0*2048kB 0*4096kB = 57928kB > Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 > hugepages_size=1048576kB > Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 > hugepages_size=2048kB > 591 total pagecache pages > 0 pages in swap cache > Swap cache stats: add 0, delete 0, find 0/0 > Free swap = 0kB > Total swap = 0kB > 1965979 pages RAM > 0 pages HighMem/MovableOnly > 342853 pages reserved > 0 pages cma reserved > Unreclaimable slab info: > Name Used Total > TIPC 1KB 7KB > SCTPv6 2KB 6KB > DCCPv6 2KB 7KB > DCCP 2KB 6KB > fib6_nodes 0KB 4KB > ip6_dst_cache 4KB 7KB > RAWv6 9KB 19KB > UDPv6 14KB 14KB > TCPv6 23KB 29KB > nf_conntrack 0KB 3KB > sd_ext_cdb 0KB 3KB > scsi_sense_cache 1056KB 1060KB > virtio_scsi_cmd 16KB 16KB > ---[ end trace 92ff4e73865c48e6 ]--- > sgpool-128 8KB 8KB > RIP: 0010:check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline] > RIP: 0010:watchdog+0x492/0x1060 kernel/hung_task.c:289 > sgpool-64 4KB 6KB > sgpool-32 2KB 7KB > Code: 44 89 b5 30 fe ff ff 48 c1 e8 03 4c 01 e8 48 89 85 e8 fd ff ff e9 f8 > 00 00 00 e8 29 f3 ff ff 48 8d 7b 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 > 0f 85 70 0a 00 00 4c 8b 73 10 bf 02 00 00 00 4c 89 > sgpool-16 1KB 3KB > RSP: 0018:ffff8881d7b37cc8 EFLAGS: 00010202 > RAX: 01a5bfffffffff51 RBX: 0d2dfffffffffa7a RCX: ffffffff817f9259 > RDX: 0000000000000000 RSI: ffffffff817f9147 RDI: 0d2dfffffffffa8a > RBP: ffff8881d7b37f00 R08: ffff8881d7bae140 R09: ffffed103b5e5b5f > sgpool-8 0KB 3KB > mqueue_inode_cache 1KB 7KB > R10: ffffed103b5e5b5f R11: ffff8881daf2dafb R12: 00000000000003d6 > R13: dffffc0000000000 R14: 1ffff1103af66fbb R15: 00000000003fffd7 > bio_post_read_ctx 14KB 15KB > FS: 0000000000000000(0000) GS:ffff8881dae00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > bio-2 14KB 15KB > jfs_mp 7KB 7KB > nfs_commit_data 3KB 7KB > CR2: 00000000004376a0 CR3: 000000016845e000 CR4: 00000000001406f0 > nfs_write_data 32KB 32KB > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > ext4_system_zone 0KB 3KB > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with > syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches
