Hello, syzbot found the following crash on: HEAD commit: f66ed1eb Merge tag 'iomap-5.7-fixes-1' of git://git.kernel.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13a4fa9c100000 kernel config: https://syzkaller.appspot.com/x/.config?x=5b075813ec8b93cd dashboard link: https://syzkaller.appspot.com/bug?extid=22b5ef302c7c40d94ea8 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12315918100000 The bug was bisected to: commit 7c4310ff56422ea43418305d22bbc5fe19150ec4 Author: NeilBrown <neilb@xxxxxxx> Date: Fri Apr 3 03:33:41 2020 +0000 SUNRPC: defer slow parts of rpc_free_client() to a workqueue. bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12176e60100000 final crash: https://syzkaller.appspot.com/x/report.txt?x=11176e60100000 console output: https://syzkaller.appspot.com/x/log.txt?x=16176e60100000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+22b5ef302c7c40d94ea8@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 7c4310ff5642 ("SUNRPC: defer slow parts of rpc_free_client() to a workqueue.") IPv6: ADDRCONF(NETDEV_CHANGE): veth1_vlan: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth0_vlan: link becomes ready ================================================================== BUG: KASAN: use-after-free in rpc_net_ns+0x222/0x230 net/sunrpc/clnt.c:1506 Read of size 8 at addr ffff8880a7c888d8 by task kworker/0:3/2690 CPU: 0 PID: 2690 Comm: kworker/0:3 Not tainted 5.7.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events rpc_free_client_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382 __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511 kasan_report+0x33/0x50 mm/kasan/common.c:625 rpc_net_ns+0x222/0x230 net/sunrpc/clnt.c:1506 rpc_clnt_remove_pipedir net/sunrpc/clnt.c:111 [inline] rpc_free_client_work+0x1a/0x60 net/sunrpc/clnt.c:892 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Allocated by task 8372: save_stack+0x1b/0x40 mm/kasan/common.c:49 set_track mm/kasan/common.c:57 [inline] __kasan_kmalloc mm/kasan/common.c:495 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x161/0x7a0 mm/slab.c:3665 kmalloc include/linux/slab.h:560 [inline] kzalloc include/linux/slab.h:669 [inline] xprt_alloc+0x2d/0x800 net/sunrpc/xprt.c:1658 xs_setup_xprt.part.0+0x56/0x2e0 net/sunrpc/xprtsock.c:2735 xs_setup_xprt net/sunrpc/xprtsock.c:2906 [inline] xs_setup_udp+0x9e/0x890 net/sunrpc/xprtsock.c:2850 xprt_create_transport+0xf9/0x480 net/sunrpc/xprt.c:1905 rpc_create+0x282/0x680 net/sunrpc/clnt.c:581 nfs_create_rpc_client+0x4eb/0x680 fs/nfs/client.c:535 nfs_init_client fs/nfs/client.c:652 [inline] nfs_init_client+0x6d/0xf0 fs/nfs/client.c:639 nfs_get_client+0x1098/0x1430 fs/nfs/client.c:429 nfs_init_server+0x305/0xf00 fs/nfs/client.c:691 nfs_create_server+0x15c/0x700 fs/nfs/client.c:978 nfs_try_get_tree+0x166/0x8d0 fs/nfs/super.c:922 nfs_get_tree+0x95a/0x13a0 fs/nfs/fs_context.c:1291 vfs_get_tree+0x89/0x2f0 fs/super.c:1547 do_new_mount fs/namespace.c:2816 [inline] do_mount+0x1306/0x1b30 fs/namespace.c:3141 __do_sys_mount fs/namespace.c:3350 [inline] __se_sys_mount fs/namespace.c:3327 [inline] __x64_sys_mount+0x18f/0x230 fs/namespace.c:3327 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Freed by task 23: save_stack+0x1b/0x40 mm/kasan/common.c:49 set_track mm/kasan/common.c:57 [inline] kasan_set_free_info mm/kasan/common.c:317 [inline] __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456 __cache_free mm/slab.c:3426 [inline] kmem_cache_free_bulk+0x7d/0x280 mm/slab.c:3721 kfree_bulk include/linux/slab.h:412 [inline] kfree_rcu_work+0x1a1/0x480 kernel/rcu/tree.c:2859 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 The buggy address belongs to the object at ffff8880a7c88000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 2264 bytes inside of 4096-byte region [ffff8880a7c88000, ffff8880a7c89000) The buggy address belongs to the page: page:ffffea00029f2200 refcount:1 mapcount:0 mapping:00000000862db9cd index:0x0 head:ffffea00029f2200 order:1 compound_mapcount:0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea00029ca708 ffffea00029a1c88 ffff8880aa002000 raw: 0000000000000000 ffff8880a7c88000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a7c88780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a7c88800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a7c88880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a7c88900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a7c88980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- 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#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches
