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Tue, 01 Dec 2020 01:33:17 -0800 (PST) From: Denis Kirjanov To: netdev@vger.kernel.org Cc: kuba@kernel.org, davem@davemloft.net Subject: [PATCH v3] net/af_unix: don't create a path for a binded socket Date: Tue, 1 Dec 2020 12:33:06 +0300 Message-Id: <20201201093306.32638-1-kda@linux-powerpc.org> X-Mailer: git-send-email 2.16.4 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org in the case of the socket which is bound to an adress there is no sense to create a path in the next attempts here is a program that shows the issue: int main() { int s; struct sockaddr_un a; s = socket(AF_UNIX, SOCK_STREAM, 0); if (s<0) perror("socket() failed\n"); printf("First bind()\n"); memset(&a, 0, sizeof(a)); a.sun_family = AF_UNIX; strncpy(a.sun_path, "/tmp/.first_bind", sizeof(a.sun_path)); if ((bind(s, (const struct sockaddr*) &a, sizeof(a))) == -1) perror("bind() failed\n"); printf("Second bind()\n"); memset(&a, 0, sizeof(a)); a.sun_family = AF_UNIX; strncpy(a.sun_path, "/tmp/.first_bind_failed", sizeof(a.sun_path)); if ((bind(s, (const struct sockaddr*) &a, sizeof(a))) == -1) perror("bind() failed\n"); } kda@SLES15-SP2:~> ./test First bind() Second bind() bind() failed : Invalid argument kda@SLES15-SP2:~> ls -la /tmp/.first_bind .first_bind .first_bind_failed Signed-off-by: Denis Kirjanov v2: move a new path creation after the address assignment check v3: fixed goto labels on the error path --- net/unix/af_unix.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 41c3303c3357..70861e9bcfd9 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1034,6 +1034,14 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) goto out; addr_len = err; + err = mutex_lock_interruptible(&u->bindlock); + if (err) + goto out; + + err = -EINVAL; + if (u->addr) + goto out_up; + if (sun_path[0]) { umode_t mode = S_IFSOCK | (SOCK_INODE(sock)->i_mode & ~current_umask()); @@ -1041,22 +1049,14 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) if (err) { if (err == -EEXIST) err = -EADDRINUSE; - goto out; + goto out_up; } } - err = mutex_lock_interruptible(&u->bindlock); - if (err) - goto out_put; - - err = -EINVAL; - if (u->addr) - goto out_up; - err = -ENOMEM; addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL); if (!addr) - goto out_up; + goto out_put; memcpy(addr->name, sunaddr, addr_len); addr->len = addr_len; @@ -1088,11 +1088,11 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) out_unlock: spin_unlock(&unix_table_lock); -out_up: - mutex_unlock(&u->bindlock); out_put: if (err) path_put(&path); +out_up: + mutex_unlock(&u->bindlock); out: return err; }