On 05.06.2019 21:42, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: b2924447 Add linux-next specific files for 20190605 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=17e867eea00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=4248d6bc70076f7d > dashboard link: https://syzkaller.appspot.com/bug?extid=83a43746cebef3508b49 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1122965aa00000 > > The bug was bisected to: > > commit db17b61765c2c63b9552d316551550557ff0fcfd > Author: J. Bruce Fields <bfields@xxxxxxxxxx> > Date: Fri May 17 13:03:38 2019 +0000 > > nfsd4: drc containerization > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=110cd22ea00000 > final crash: https://syzkaller.appspot.com/x/report.txt?x=130cd22ea00000 > console output: https://syzkaller.appspot.com/x/log.txt?x=150cd22ea00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+83a43746cebef3508b49@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: db17b61765c2 ("nfsd4: drc containerization") > > ================================================================== > BUG: KASAN: use-after-free in __list_del_entry_valid+0xe6/0xf5 lib/list_debug.c:51 > Read of size 8 at addr ffff88808a5bd128 by task syz-executor.2/12471 > > CPU: 0 PID: 12471 Comm: syz-executor.2 Not tainted 5.2.0-rc3-next-20190605 #9 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351 > __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482 > kasan_report+0x12/0x20 mm/kasan/common.c:614 > __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 > __list_del_entry_valid+0xe6/0xf5 lib/list_debug.c:51 > __list_del_entry include/linux/list.h:117 [inline] > list_del include/linux/list.h:125 [inline] > unregister_shrinker+0xb2/0x2e0 mm/vmscan.c:443 > nfsd_reply_cache_shutdown+0x26/0x360 fs/nfsd/nfscache.c:194 > nfsd_exit_net+0x170/0x4b0 fs/nfsd/nfsctl.c:1272 > ops_exit_list.isra.0+0xaa/0x150 net/core/net_namespace.c:154 > setup_net+0x400/0x740 net/core/net_namespace.c:333 > copy_net_ns+0x1df/0x340 net/core/net_namespace.c:439 > create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:107 > unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:206 > ksys_unshare+0x444/0x980 kernel/fork.c:2718 > __do_sys_unshare kernel/fork.c:2786 [inline] > __se_sys_unshare kernel/fork.c:2784 [inline] > __x64_sys_unshare+0x31/0x40 kernel/fork.c:2784 > do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x459279 > Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f7ae73e1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 > RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000459279 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000 > RBP: 000000000075bfc0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7ae73e26d4 > R13: 00000000004c84ef R14: 00000000004decb0 R15: 00000000ffffffff > > Allocated by task 12460: > save_stack+0x23/0x90 mm/kasan/common.c:71 > set_track mm/kasan/common.c:79 [inline] > __kasan_kmalloc mm/kasan/common.c:489 [inline] > __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 > kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503 > __do_kmalloc mm/slab.c:3654 [inline] > __kmalloc+0x15c/0x740 mm/slab.c:3663 > kmalloc include/linux/slab.h:552 [inline] > kzalloc include/linux/slab.h:742 [inline] > ops_init+0xff/0x410 net/core/net_namespace.c:120 > setup_net+0x2d3/0x740 net/core/net_namespace.c:316 > copy_net_ns+0x1df/0x340 net/core/net_namespace.c:439 > create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:107 > unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:206 > ksys_unshare+0x444/0x980 kernel/fork.c:2718 > __do_sys_unshare kernel/fork.c:2786 [inline] > __se_sys_unshare kernel/fork.c:2784 [inline] > __x64_sys_unshare+0x31/0x40 kernel/fork.c:2784 > do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 12460: > save_stack+0x23/0x90 mm/kasan/common.c:71 > set_track mm/kasan/common.c:79 [inline] > __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 > kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 > __cache_free mm/slab.c:3426 [inline] > kfree+0x106/0x2a0 mm/slab.c:3753 > ops_init+0xd1/0x410 net/core/net_namespace.c:135 > setup_net+0x2d3/0x740 net/core/net_namespace.c:316 > copy_net_ns+0x1df/0x340 net/core/net_namespace.c:439 > create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:107 > unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:206 > ksys_unshare+0x444/0x980 kernel/fork.c:2718 > __do_sys_unshare kernel/fork.c:2786 [inline] > __se_sys_unshare kernel/fork.c:2784 [inline] > __x64_sys_unshare+0x31/0x40 kernel/fork.c:2784 > do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > The buggy address belongs to the object at ffff88808a5bcdc0 > which belongs to the cache kmalloc-1k of size 1024 > The buggy address is located 872 bytes inside of > 1024-byte region [ffff88808a5bcdc0, ffff88808a5bd1c0) > The buggy address belongs to the page: > page:ffffea0002296f00 refcount:1 mapcount:0 mapping:ffff8880aa400ac0 index:0x0 compound_mapcount: 0 > flags: 0x1fffc0000010200(slab|head) > raw: 01fffc0000010200 ffffea000249ea08 ffffea000235a588 ffff8880aa400ac0 > raw: 0000000000000000 ffff88808a5bc040 0000000100000007 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff88808a5bd000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff88808a5bd080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff88808a5bd100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff88808a5bd180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > ffff88808a5bd200: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 > ================================================================== This may be connected with that shrinker unregistering is forgotten on error path. --- diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index ea39497205f0..8705e7d09717 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -181,6 +181,7 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) return 0; out_nomem: + unregister_shrinker(&nn->nfsd_reply_cache_shrinker); printk(KERN_ERR "nfsd: failed to allocate reply cache\n"); return -ENOMEM; }
