@@ -561,7 +561,7 @@ 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;
@@ -571,9 +571,14 @@ 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) {
/*
@@ -588,7 +593,6 @@ 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);
if (file == ppp->owner)
@@ -600,15 +604,13 @@ 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) {
@@ -630,17 +632,16 @@ 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:
@@ -811,7 +812,10 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
default:
err = -ENOTTY;
}
+
+out:
mutex_unlock(&ppp_mutex);
+
return err;
}
@@ -824,7 +828,6 @@ 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 */
@@ -875,7 +878,7 @@ static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
default:
err = -ENOTTY;
}
- mutex_unlock(&ppp_mutex);
+
return err;
}
This is a note to let you know that I have just added a patch titled ppp: ensure file->private_data can't be overridden to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt27. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ---8<------------------------------------------------------------ From 8f9be9154d30580bec250f30be96131396d1bdbe Mon Sep 17 00:00:00 2001 From: Guillaume Nault <g.nault@alphalink.fr> Date: Mon, 14 Mar 2016 21:17:16 +0100 Subject: ppp: ensure file->private_data can't be overridden commit e8e56ffd9d2973398b60ece1f1bebb8d67b4d032 upstream. 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> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/net/ppp/ppp_generic.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-)