Re: [PATCH v2 0/3] auth_gss: netns refcount leaks when use-gss-proxy==1

[Wenbin Zeng]

On Tue, May 14, 2019 at 09:03:31PM -0400, J. Bruce Fields wrote:
> Whoops, I was slow to test these.  I'm getting failuring krb5 nfs
> mounts, and the following the server's logs.  Dropping the three patches
> for now.
My bad, I should have found it earlier. Thank you for testing it, Bruce.

I figured it out, the problem that you saw is due to the following code:
the if-condition is incorrect here because sn->gssp_clnt==NULL doesn't mean
inexistence of 'use-gss-proxy':

-static __net_exit void rpcsec_gss_exit_net(struct net *net)
+static void rpcsec_gss_evict_net(struct net *net)
 {
-       gss_svc_shutdown_net(net);
+       struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+       if (sn->gssp_clnt)
+               gss_svc_shutdown_net(net);
 }

Simply using the original logic in rpcsec_gss_exit_net() should be fine,
i.e.:

-static __net_exit void rpcsec_gss_exit_net(struct net *net)
+static void rpcsec_gss_evict_net(struct net *net)
 {
        gss_svc_shutdown_net(net);
 }

I'm going to submit v3 soon.

Wenbin.

> 
> --b.
> 
> [   40.894408] remove_proc_entry: removing non-empty directory 'net/rpc', leaking at least 'use-gss-proxy'
> [   40.897352] WARNING: CPU: 2 PID: 31 at fs/proc/generic.c:683 remove_proc_entry+0x17d/0x190
> [   40.899373] Modules linked in: nfsd nfs_acl lockd grace auth_rpcgss sunrpc
> [   40.901335] CPU: 2 PID: 31 Comm: kworker/u8:1 Not tainted 5.1.0-10733-g4f10d1cb695e #2220
> [   40.903759] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20180724_192412-buildhw-07.phx2.fedoraproject.org-1.fc29 04/01/2014
> [   40.906972] Workqueue: netns cleanup_net
> [   40.907828] RIP: 0010:remove_proc_entry+0x17d/0x190
> [   40.908904] Code: 52 82 48 85 c0 48 8d 90 48 ff ff ff 48 0f 45 c2 48 8b 93 a8 00 00 00 4c 8b 80 d0 00 00 00 48 8b 92 d0 00 00 00 e8 a7 24 dc ff <0f> 0b e9 52 ff ff ff e8 a7 21 dc ff 0f 1f 80 00 00 00 00 0f 1f 44
> [   40.912689] RSP: 0018:ffffc90000123d80 EFLAGS: 00010282
> [   40.913495] RAX: 0000000000000000 RBX: ffff888079f96e40 RCX: 0000000000000000
> [   40.914747] RDX: ffff88807fd24e80 RSI: ffff88807fd165b8 RDI: 00000000ffffffff
> [   40.916107] RBP: ffff888079f96ef0 R08: 0000000000000000 R09: 0000000000000000
> [   40.917253] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88807cd76d68
> [   40.918508] R13: ffffffffa0057000 R14: ffff8880683db200 R15: ffffffff82970240
> [   40.919642] FS:  0000000000000000(0000) GS:ffff88807fd00000(0000) knlGS:0000000000000000
> [   40.920956] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   40.921867] CR2: 00007f9d70010cb8 CR3: 000000007cc5c006 CR4: 00000000001606e0
> [   40.923044] Call Trace:
> [   40.923364]  sunrpc_exit_net+0xcc/0x190 [sunrpc]
> [   40.924069]  ops_exit_list.isra.0+0x36/0x70
> [   40.924713]  cleanup_net+0x1cb/0x2c0
> [   40.925182]  process_one_work+0x219/0x620
> [   40.925780]  worker_thread+0x3c/0x390
> [   40.926312]  ? process_one_work+0x620/0x620
> [   40.927015]  kthread+0x11d/0x140
> [   40.927430]  ? kthread_park+0x80/0x80
> [   40.927822]  ret_from_fork+0x3a/0x50
> [   40.928281] irq event stamp: 11688
> [   40.928780] hardirqs last  enabled at (11687): [<ffffffff811225fe>] console_unlock+0x41e/0x590
> [   40.930319] hardirqs last disabled at (11688): [<ffffffff81001b2c>] trace_hardirqs_off_thunk+0x1a/0x1c
> [   40.932123] softirqs last  enabled at (11684): [<ffffffff820002c5>] __do_softirq+0x2c5/0x4c5
> [   40.933657] softirqs last disabled at (11673): [<ffffffff810bf970>] irq_exit+0x80/0x90
>