From 6755aebaaf9fc5416acfd4578ab7a1e122ecbc74 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 6 Nov 2009 00:23:01 +0000 Subject: [PATCH] can: should not use __dev_get_by_index() without locks bcm_proc_getifname() is called with RTNL and dev_base_lock not held. It calls __dev_get_by_index() without locks, and this is illegal (might crash) Close the race by holding dev_base_lock and copying dev->name in the protected section. Signed-off-by: Eric Dumazet Signed-off-by: Oliver Hartkopp Signed-off-by: David S. Miller --- net/can/bcm.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/net/can/bcm.c b/net/can/bcm.c index 597da4f8f888..e8d58f33fe09 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -132,23 +132,27 @@ static inline struct bcm_sock *bcm_sk(const struct sock *sk) /* * procfs functions */ -static char *bcm_proc_getifname(int ifindex) +static char *bcm_proc_getifname(char *result, int ifindex) { struct net_device *dev; if (!ifindex) return "any"; - /* no usage counting */ + read_lock(&dev_base_lock); dev = __dev_get_by_index(&init_net, ifindex); if (dev) - return dev->name; + strcpy(result, dev->name); + else + strcpy(result, "???"); + read_unlock(&dev_base_lock); - return "???"; + return result; } static int bcm_proc_show(struct seq_file *m, void *v) { + char ifname[IFNAMSIZ]; struct sock *sk = (struct sock *)m->private; struct bcm_sock *bo = bcm_sk(sk); struct bcm_op *op; @@ -157,7 +161,7 @@ static int bcm_proc_show(struct seq_file *m, void *v) seq_printf(m, " / sk %p", sk); seq_printf(m, " / bo %p", bo); seq_printf(m, " / dropped %lu", bo->dropped_usr_msgs); - seq_printf(m, " / bound %s", bcm_proc_getifname(bo->ifindex)); + seq_printf(m, " / bound %s", bcm_proc_getifname(ifname, bo->ifindex)); seq_printf(m, " <<<\n"); list_for_each_entry(op, &bo->rx_ops, list) { @@ -169,7 +173,7 @@ static int bcm_proc_show(struct seq_file *m, void *v) continue; seq_printf(m, "rx_op: %03X %-5s ", - op->can_id, bcm_proc_getifname(op->ifindex)); + op->can_id, bcm_proc_getifname(ifname, op->ifindex)); seq_printf(m, "[%d]%c ", op->nframes, (op->flags & RX_CHECK_DLC)?'d':' '); if (op->kt_ival1.tv64) @@ -194,7 +198,8 @@ static int bcm_proc_show(struct seq_file *m, void *v) list_for_each_entry(op, &bo->tx_ops, list) { seq_printf(m, "tx_op: %03X %s [%d] ", - op->can_id, bcm_proc_getifname(op->ifindex), + op->can_id, + bcm_proc_getifname(ifname, op->ifindex), op->nframes); if (op->kt_ival1.tv64) -- 2.30.2