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authorGuillaume Nault <g.nault@alphalink.fr>2016-03-14 21:17:16 +0100
committerDavid S. Miller <davem@davemloft.net>2016-03-16 19:35:06 -0400
commite8e56ffd9d2973398b60ece1f1bebb8d67b4d032 (patch)
tree06154afcd07d48f65e66a388f0f8634efdd6cfbf /drivers/net/ppp
parentc8f5d29899901cea94bf4b8cf721e1b83e51174e (diff)
downloadlinux-e8e56ffd9d2973398b60ece1f1bebb8d67b4d032.tar.bz2
ppp: ensure file->private_data can't be overridden
Locking ppp_mutex must be done before dereferencing file->private_data, otherwise it could be modified before ppp_unattached_ioctl() takes the lock. This could lead ppp_unattached_ioctl() to override ->private_data, thus leaking reference to the ppp_file previously pointed to. v2: lock all ppp_ioctl() instead of just checking private_data in ppp_unattached_ioctl(), to avoid ambiguous behaviour. Fixes: f3ff8a4d80e8 ("ppp: push BKL down into the driver") Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ppp')
-rw-r--r--drivers/net/ppp/ppp_generic.c31
1 files changed, 17 insertions, 14 deletions
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 931836e09a6b..4fd861063ed4 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -575,7 +575,7 @@ static int get_filter(void __user *arg, struct sock_filter **p)
static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
- struct ppp_file *pf = file->private_data;
+ struct ppp_file *pf;
struct ppp *ppp;
int err = -EFAULT, val, val2, i;
struct ppp_idle idle;
@@ -585,9 +585,14 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
void __user *argp = (void __user *)arg;
int __user *p = argp;
- if (!pf)
- return ppp_unattached_ioctl(current->nsproxy->net_ns,
- pf, file, cmd, arg);
+ mutex_lock(&ppp_mutex);
+
+ pf = file->private_data;
+ if (!pf) {
+ err = ppp_unattached_ioctl(current->nsproxy->net_ns,
+ pf, file, cmd, arg);
+ goto out;
+ }
if (cmd == PPPIOCDETACH) {
/*
@@ -602,7 +607,6 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
* this fd and reopening /dev/ppp.
*/
err = -EINVAL;
- mutex_lock(&ppp_mutex);
if (pf->kind == INTERFACE) {
ppp = PF_TO_PPP(pf);
rtnl_lock();
@@ -616,15 +620,13 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
} else
pr_warn("PPPIOCDETACH file->f_count=%ld\n",
atomic_long_read(&file->f_count));
- mutex_unlock(&ppp_mutex);
- return err;
+ goto out;
}
if (pf->kind == CHANNEL) {
struct channel *pch;
struct ppp_channel *chan;
- mutex_lock(&ppp_mutex);
pch = PF_TO_CHANNEL(pf);
switch (cmd) {
@@ -646,17 +648,16 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
err = chan->ops->ioctl(chan, cmd, arg);
up_read(&pch->chan_sem);
}
- mutex_unlock(&ppp_mutex);
- return err;
+ goto out;
}
if (pf->kind != INTERFACE) {
/* can't happen */
pr_err("PPP: not interface or channel??\n");
- return -EINVAL;
+ err = -EINVAL;
+ goto out;
}
- mutex_lock(&ppp_mutex);
ppp = PF_TO_PPP(pf);
switch (cmd) {
case PPPIOCSMRU:
@@ -831,7 +832,10 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
default:
err = -ENOTTY;
}
+
+out:
mutex_unlock(&ppp_mutex);
+
return err;
}
@@ -844,7 +848,6 @@ static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
struct ppp_net *pn;
int __user *p = (int __user *)arg;
- mutex_lock(&ppp_mutex);
switch (cmd) {
case PPPIOCNEWUNIT:
/* Create a new ppp unit */
@@ -894,7 +897,7 @@ static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
default:
err = -ENOTTY;
}
- mutex_unlock(&ppp_mutex);
+
return err;
}