From: Guillaume Nault <g.nault@xxxxxxxxxxxx>
This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit e8e56ffd9d2973398b60ece1f1bebb8d67b4d032 ]
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@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
drivers/net/ppp/ppp_generic.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index cfe49a0..221334a 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -563,7 +563,7 @@ 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;
@@ -573,9 +573,14 @@ 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) {
/*
@@ -590,7 +595,6 @@ 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)
@@ -602,15 +606,13 @@ 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) {
@@ -632,17 +634,16 @@ 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:
@@ -817,7 +818,10 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
default:
err = -ENOTTY;
}
+
+out:
mutex_unlock(&ppp_mutex);
+
return err;
}
@@ -830,7 +834,6 @@ 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 */
@@ -881,7 +884,7 @@ static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
default:
err = -ENOTTY;
}
- mutex_unlock(&ppp_mutex);
+
return err;
}
--
2.5.0
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