Re: [PATCH net] SUNRPC: Fix local socket leak in xs_local_setup_socket()

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在 2022/4/27 2:51, Trond Myklebust 写道:
On Tue, 2022-04-26 at 21:20 +0800, Wang Hai wrote:
If the connection to a local endpoint in xs_local_setup_socket()
fails,
fput() is missing in the error path, which will result in a socket
leak.
It can be reproduced in simple script below.

while true
do
         systemctl stop rpcbind.service
         systemctl stop rpc-statd.service
         systemctl stop nfs-server.service

         systemctl restart rpcbind.service
         systemctl restart rpc-statd.service
         systemctl restart nfs-server.service
done

When executing the script, you can observe that the
"cat /proc/net/unix | wc -l" count keeps growing.

Add the missing fput(), and restore transport to old socket.

Signed-off-by: Wang Hai <wanghai38@xxxxxxxxxx>
---
  net/sunrpc/xprtsock.c | 20 ++++++++++++++++++--
  1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 0f39e08ee580..7219c545385e 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1819,6 +1819,9 @@ static int xs_local_finish_connecting(struct
rpc_xprt *xprt,
  {
         struct sock_xprt *transport = container_of(xprt, struct
sock_xprt,
   xprt);
+       struct socket *trans_sock = NULL;
+       struct sock *trans_inet = NULL;
+       int ret;
        if (!transport->inet) {
                 struct sock *sk = sock->sk;
@@ -1835,6 +1838,9 @@ static int xs_local_finish_connecting(struct
rpc_xprt *xprt,
                xprt_clear_connected(xprt); +               trans_sock = transport->sock;
+               trans_inet = transport->inet;
+
Both values are NULL here
Got it, thanks

                 /* Reset to new socket */
                 transport->sock = sock;
                 transport->inet = sk;
@@ -1844,7 +1850,14 @@ static int xs_local_finish_connecting(struct
rpc_xprt *xprt,
        xs_stream_start_connect(transport); -       return kernel_connect(sock, xs_addr(xprt), xprt->addrlen, 0);
+       ret = kernel_connect(sock, xs_addr(xprt), xprt->addrlen, 0);
+       /* Restore to old socket */
+       if (ret && trans_inet) {
+               transport->sock = trans_sock;
+               transport->inet = trans_inet;
+       }
+
+       return ret;
  }
 /**
@@ -1887,7 +1900,7 @@ static int xs_local_setup_socket(struct
sock_xprt *transport)
                 xprt->stat.connect_time += (long)jiffies -
                                            xprt->stat.connect_start;
                 xprt_set_connected(xprt);
-               break;
+               goto out;
         case -ENOBUFS:
                 break;
         case -ENOENT:
@@ -1904,6 +1917,9 @@ static int xs_local_setup_socket(struct
sock_xprt *transport)
                                 xprt-
address_strings[RPC_DISPLAY_ADDR]);
         }
+       transport->file = NULL;
+       fput(filp);
Please just call xprt_force_disconnect() so that this can be cleaned up
from 	a safe context.

Hi, Trond

Thank you for your advice, I tried this, but it doesn't seem to

work and an error is reported. I'll analyze why this happens

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 0f39e08ee580..3d1387b2cfbf 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1887,7 +1887,7 @@ static int xs_local_setup_socket(struct sock_xprt *transport)
                xprt->stat.connect_time += (long)jiffies -
xprt->stat.connect_start;
                xprt_set_connected(xprt);
-               break;
+               goto out;
        case -ENOBUFS:
                break;
        case -ENOENT:
@@ -1904,6 +1904,8 @@ static int xs_local_setup_socket(struct sock_xprt *transport)
xprt->address_strings[RPC_DISPLAY_ADDR]);
        }

+       xprt_force_disconnect(xprt);
+
 out:
        xprt_clear_connecting(xprt);
        xprt_wake_pending_tasks(xprt, status);


[ 2541.763895][ T8289] ------------[ cut here ]------------
[ 2541.765829][ T8289] WARNING: CPU: 0 PID: 8289 at kernel/workqueue.c:1499 __queue_work+0x72a/0x810
[ 2541.768862][ T8289] Modules linked in:
[ 2541.770085][ T8289] CPU: 0 PID: 8289 Comm: gssproxy Tainted: G        W         5.17.0+ #762 [ 2541.772724][ T8289] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 2541.773788][ T8289] RIP: 0010:__queue_work+0x72a/0x810
[ 2541.773788][ T8289] Code: 48 c7 c7 f8 7b b8 84 c6 05 b1 f4 39 04 01 e8 ad 65 05 00 e9 7f fe ff ff e8 33 94 11 00 4c 8b 33 e9 ff f9 ff ff e8 26 94 11 00 <0f> 0b e9 d2 fa ff ff e8 1a 94 11 00 4c 8d 7b 68 41 83 cc 02 e9 aa
[ 2541.773788][ T8289] RSP: 0018:ffffc900083dfb20 EFLAGS: 00010093
[ 2541.773788][ T8289] RAX: 0000000000000000 RBX: ffff8881002a7900 RCX: 0000000000000000 [ 2541.773788][ T8289] RDX: ffff88824e091b40 RSI: ffffffff8119be6a RDI: ffffc900083dfb07 [ 2541.773788][ T8289] RBP: ffffc900083dfb60 R08: 0000000000000001 R09: 0000000000000000 [ 2541.773788][ T8289] R10: 0000000000000000 R11: 6e75732f74656e5b R12: 0000000000000000 [ 2541.773788][ T8289] R13: ffff88811a284668 R14: ffff888237c2d440 R15: ffff888243141c00 [ 2541.773788][ T8289] FS:  00007f3bb3f9dc40(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
[ 2541.773788][ T8289] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2541.773788][ T8289] CR2: 00007f3bb04a72e0 CR3: 00000002602c5000 CR4: 00000000000006f0 [ 2541.773788][ T8289] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 2541.773788][ T8289] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 2541.773788][ T8289] Call Trace:
[ 2541.773788][ T8289]  <TASK>
[ 2541.773788][ T8289]  queue_work_on+0x88/0x90
[ 2541.773788][ T8289]  xprt_schedule_autoclose_locked+0x7a/0xb0
[ 2541.773788][ T8289]  xprt_force_disconnect+0x53/0x150
[ 2541.773788][ T8289]  xs_local_setup_socket+0x131/0x3e0
[ 2541.823215][ T8289]  xs_setup_local+0x24b/0x280
[ 2541.823215][ T8289]  xprt_create_transport+0xb0/0x340
[ 2541.823215][ T8289]  rpc_create+0x104/0x2b0
[ 2541.823215][ T8289]  gssp_rpc_create+0x93/0xe0
[ 2541.823215][ T8289]  set_gssp_clnt+0xd9/0x230
[ 2541.823215][ T8289]  write_gssp+0xb9/0x130
[ 2541.823215][ T8289]  ? lock_acquire+0x1de/0x2f0
[ 2541.823215][ T8289]  proc_reg_write+0xd2/0x110
[ 2541.823215][ T8289]  ? set_gss_proxy+0x1d0/0x1d0
[ 2541.823215][ T8289]  ? proc_reg_compat_ioctl+0x100/0x100
[ 2541.823215][ T8289]  vfs_write+0x11d/0x4b0
[ 2541.841496][ T8289]  ksys_write+0xe0/0x130
[ 2541.841496][ T8289]  __x64_sys_write+0x23/0x30
[ 2541.841496][ T8289]  do_syscall_64+0x34/0xb0
[ 2541.841496][ T8289]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 2541.841496][ T8289] RIP: 0033:0x7f3bb0811280
[ 2541.841496][ T8289] Code: 00 c3 0f 1f 84 00 00 00 00 00 48 8b 05 c1 8c 20 00 c3 0f 1f 84 00 00 00 00 00 83 3d 09 cf 20 00 00 75 10 b8 01 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 6e fd ff ff 48 89 04 24 [ 2541.841496][ T8289] RSP: 002b:00007ffc59024c98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 2541.841496][ T8289] RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f3bb0811280 [ 2541.841496][ T8289] RDX: 0000000000000001 RSI: 00007ffc59024ca6 RDI: 0000000000000009 [ 2541.841496][ T8289] RBP: 0000000000000000 R08: 0000000000000020 R09: 0000000000000060 [ 2541.841496][ T8289] R10: 0000561545627900 R11: 0000000000000246 R12: 0000561545630580 [ 2541.841496][ T8289] R13: 00007ffc59024fd0 R14: 0000000000000000 R15: 0000000000000000
[ 2541.841496][ T8289]  </TASK>
[ 2541.841496][ T8289] irq event stamp: 0
[ 2541.841496][ T8289] hardirqs last  enabled at (0): [<0000000000000000>] 0x0 [ 2541.841496][ T8289] hardirqs last disabled at (0): [<ffffffff81165e25>] copy_process+0xb35/0x2410 [ 2541.841496][ T8289] softirqs last  enabled at (0): [<ffffffff81165e25>] copy_process+0xb35/0x2410 [ 2541.841496][ T8289] softirqs last disabled at (0): [<0000000000000000>] 0x0
[ 2541.841496][ T8289] ---[ end trace 0000000000000000 ]---
+
  out:
         xprt_clear_connecting(xprt);
         xprt_wake_pending_tasks(xprt, status);

--
Wang Hai




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