lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 6 Jan 2020 21:47:12 -0800 From: Bjorn Andersson <bjorn.andersson@...aro.org> To: "David S. Miller" <davem@...emloft.net> Cc: Arun Kumar Neelakantam <aneela@...eaurora.org>, Chris Lew <clew@...eaurora.org>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org Subject: [PATCH v3 4/5] net: qrtr: Make qrtr_port_lookup() use RCU The important part of qrtr_port_lookup() wrt synchronization is that the function returns a reference counted struct qrtr_sock, or fail. As such we need only to ensure that an decrement of the object's refcount happens inbetween the finding of the object in the idr and qrtr_port_lookup()'s own increment of the object. By using RCU and putting a synchronization point after we remove the mapping from the idr, but before it can be released we achieve this - with the benefit of not having to hold the mutex in qrtr_port_lookup(). Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org> --- Changes since v2: - None net/qrtr/qrtr.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c index c2bbfa7ec6e2..aae24c1d8531 100644 --- a/net/qrtr/qrtr.c +++ b/net/qrtr/qrtr.c @@ -641,11 +641,11 @@ static struct qrtr_sock *qrtr_port_lookup(int port) if (port == QRTR_PORT_CTRL) port = 0; - mutex_lock(&qrtr_port_lock); + rcu_read_lock(); ipc = idr_find(&qrtr_ports, port); if (ipc) sock_hold(&ipc->sk); - mutex_unlock(&qrtr_port_lock); + rcu_read_unlock(); return ipc; } @@ -687,6 +687,10 @@ static void qrtr_port_remove(struct qrtr_sock *ipc) mutex_lock(&qrtr_port_lock); idr_remove(&qrtr_ports, port); mutex_unlock(&qrtr_port_lock); + + /* Ensure that if qrtr_port_lookup() did enter the RCU read section we + * wait for it to up increment the refcount */ + synchronize_rcu(); } /* Assign port number to socket. -- 2.24.0
Powered by blists - more mailing lists