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From:   Wang Ming <machel@vivo.com>
To:     Christine Caulfield <ccaulfie@redhat.com>,
        David Teigland <teigland@redhat.com>, cluster-devel@redhat.com,
        linux-kernel@vger.kernel.org
Cc:     opensource.kernel@vivo.com, gregkh@linuxfoundation.org,
        Wang Ming <machel@vivo.com>
Subject: [PATCH v1] fs:dlm:Fix potential null pointer dereference on pointer
Date:   Fri, 16 Jun 2023 10:48:24 +0800
Message-Id: <20230616024836.577-1-machel@vivo.com>
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Before dereferencing the pointer, first judge whether
it is NULL, if it is NULL, there is no need to dereference.
Fix the following coccicheck ERROR:

fs/dlm/lowcomms.c:1082:26-28: ERROR: newcon -> sock is NULL
but dereferenced.

Signed-off-by: Wang Ming <machel@vivo.com>
---
 fs/dlm/lowcomms.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 3d3802c47..0a2d1b5ab 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1079,7 +1079,18 @@ static int accept_from_sock(void)
        sock_set_mark(newsock->sk, mark);

        down_write(&newcon->sock_lock);
-       if (newcon->sock) {
+       if (newcon->sock =3D=3D NULL) {
+               /*  accept copies the sk after we've saved the callbacks, s=
o we
+                *  don't want to save them a second time or comm errors wi=
ll
+                *  result in calling sk_error_report recursively.
+                */
+               add_sock(newsock, newcon);
+
+               /* check if we receved something while adding */
+               lock_sock(newcon->sock->sk);
+               lowcomms_queue_rwork(newcon);
+               release_sock(newcon->sock->sk);
+       } else {
                struct connection *othercon =3D newcon->othercon;

                if (!othercon) {
@@ -1110,17 +1121,7 @@ static int accept_from_sock(void)
                release_sock(othercon->sock->sk);
                up_write(&othercon->sock_lock);
        }
-       else {
-               /* accept copies the sk after we've saved the callbacks, so=
 we
-                  don't want to save them a second time or comm errors wil=
l
-                  result in calling sk_error_report recursively. */
-               add_sock(newsock, newcon);

-               /* check if we receved something while adding */
-               lock_sock(newcon->sock->sk);
-               lowcomms_queue_rwork(newcon);
-               release_sock(newcon->sock->sk);
-       }
        up_write(&newcon->sock_lock);
        srcu_read_unlock(&connections_srcu, idx);

--
2.25.1


________________________________
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