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Date: Wed, 2 Feb 2022 20:47:09 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: Duoming Zhou <duoming@....edu.cn>
Cc: linux-hams@...r.kernel.org, jreuter@...na.de, ralf@...ux-mips.org,
davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [Fixes] ax25: add refcount in ax25_dev to avoid UAF bugs
Hi Duoming Zhou,
The original patch was already applied so you need to just send the
fixes by themselves on top of the net-next git tree.
> ---
> include/net/ax25.h | 12 ++++++++++++
> net/ax25/af_ax25.c | 20 ++++++++++++++++----
> net/ax25/ax25_dev.c | 33 +++++++++++++++++++++++++++------
> net/ax25/ax25_route.c | 27 ++++++++++++++++++++++-----
> 4 files changed, 77 insertions(+), 15 deletions(-)
>
> diff --git a/include/net/ax25.h b/include/net/ax25.h
> index 526e4958919..1a38b1ad529 100644
> --- a/include/net/ax25.h
> +++ b/include/net/ax25.h
> @@ -239,6 +239,7 @@ typedef struct ax25_dev {
> #if defined(CONFIG_AX25_DAMA_SLAVE) || defined(CONFIG_AX25_DAMA_MASTER)
> ax25_dama_info dama;
> #endif
> + refcount_t refcount;
> } ax25_dev;
>
> typedef struct ax25_cb {
> @@ -293,6 +294,17 @@ static __inline__ void ax25_cb_put(ax25_cb *ax25)
> }
> }
>
> +static inline void ax25_dev_hold(ax25_dev *ax25_dev)
> +{
> + refcount_inc(&ax25_dev->refcount);
> +}
> +
> +static inline void ax25_dev_put(ax25_dev *ax25_dev)
> +{
> + if (refcount_dec_and_test(&ax25_dev->refcount))
> + kfree(ax25_dev);
> +}
> +
Forget about these cleanups for now. Just fix the reference leaks on
error.
> static inline __be16 ax25_type_trans(struct sk_buff *skb, struct net_device *dev)
> {
> skb->dev = dev;
> diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
> index 44a8730c26a..7463bbd4e63 100644
> --- a/net/ax25/af_ax25.c
> +++ b/net/ax25/af_ax25.c
> @@ -91,6 +91,7 @@ static void ax25_kill_by_device(struct net_device *dev)
> spin_unlock_bh(&ax25_list_lock);
> lock_sock(sk);
> s->ax25_dev = NULL;
> + ax25_dev_put(ax25_dev);
> release_sock(sk);
> ax25_disconnect(s, ENETUNREACH);
> spin_lock_bh(&ax25_list_lock);
> @@ -358,21 +359,31 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg)
> if (copy_from_user(&ax25_ctl, arg, sizeof(ax25_ctl)))
> return -EFAULT;
>
> - if ((ax25_dev = ax25_addr_ax25dev(&ax25_ctl.port_addr)) == NULL)
> + ax25_dev = ax25_addr_ax25dev(&ax25_ctl.port_addr);
> + if (ax25_dev == NULL) {
> + ax25_dev_put(ax25_dev);
This one will lead to a NULL dereference. These NULL dereferences are
> return -ENODEV;
> + }
>
> - if (ax25_ctl.digi_count > AX25_MAX_DIGIS)
> + if (ax25_ctl.digi_count > AX25_MAX_DIGIS) {
> + ax25_dev_put(ax25_dev);
> return -EINVAL;
> + }
>
> - if (ax25_ctl.arg > ULONG_MAX / HZ && ax25_ctl.cmd != AX25_KILL)
> + if (ax25_ctl.arg > ULONG_MAX / HZ && ax25_ctl.cmd != AX25_KILL) {
> + ax25_dev_put(ax25_dev);
> return -EINVAL;
> + }
>
> digi.ndigi = ax25_ctl.digi_count;
> for (k = 0; k < digi.ndigi; k++)
> digi.calls[k] = ax25_ctl.digi_addr[k];
>
> - if ((ax25 = ax25_find_cb(&ax25_ctl.source_addr, &ax25_ctl.dest_addr, &digi, ax25_dev->dev)) == NULL)
> + ax25 = ax25_find_cb(&ax25_ctl.source_addr, &ax25_ctl.dest_addr, &digi, ax25_dev->dev);
> + if (ax25 == NULL) {
> + ax25_dev_put(ax25_dev);
Don't do this.
> return -ENOTCONN;
> + }
>
> switch (ax25_ctl.cmd) {
> case AX25_KILL:
> @@ -439,6 +450,7 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg)
> }
>
> out_put:
> + ax25_dev_put(ax25_dev);
> ax25_cb_put(ax25);
> return ret;
>
> diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
> index 256fadb94df..77d9aa2ccab 100644
> --- a/net/ax25/ax25_dev.c
> +++ b/net/ax25/ax25_dev.c
> @@ -37,6 +37,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
> for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
> if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
> res = ax25_dev;
> + ax25_dev_hold(ax25_dev);
> }
> spin_unlock_bh(&ax25_dev_lock);
>
> @@ -56,6 +57,7 @@ void ax25_dev_device_up(struct net_device *dev)
> return;
> }
>
> + refcount_set(&ax25_dev->refcount, 1);
> dev->ax25_ptr = ax25_dev;
> ax25_dev->dev = dev;
> dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC);
> @@ -83,6 +85,7 @@ void ax25_dev_device_up(struct net_device *dev)
> spin_lock_bh(&ax25_dev_lock);
> ax25_dev->next = ax25_dev_list;
> ax25_dev_list = ax25_dev;
> + ax25_dev_hold(ax25_dev);
> spin_unlock_bh(&ax25_dev_lock);
>
> ax25_register_dev_sysctl(ax25_dev);
> @@ -111,21 +114,23 @@ void ax25_dev_device_down(struct net_device *dev)
> s->forward = NULL;
>
> if ((s = ax25_dev_list) == ax25_dev) {
> + ax25_dev_put(ax25_dev_list);
Just leave the style changes until later. I'm sorry I brought it up.
> ax25_dev_list = s->next;
> spin_unlock_bh(&ax25_dev_lock);
> dev->ax25_ptr = NULL;
> dev_put_track(dev, &ax25_dev->dev_tracker);
> - kfree(ax25_dev);
> + ax25_dev_put(ax25_dev);
> return;
> }
>
> while (s != NULL && s->next != NULL) {
> if (s->next == ax25_dev) {
> + ax25_dev_put(s->next);
> s->next = ax25_dev->next;
> spin_unlock_bh(&ax25_dev_lock);
> dev->ax25_ptr = NULL;
> dev_put_track(dev, &ax25_dev->dev_tracker);
> - kfree(ax25_dev);
> + ax25_dev_put(ax25_dev);
> return;
> }
>
> @@ -133,31 +138,47 @@ void ax25_dev_device_down(struct net_device *dev)
> }
> spin_unlock_bh(&ax25_dev_lock);
> dev->ax25_ptr = NULL;
> + ax25_dev_put(ax25_dev);
> }
>
> int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd)
> {
> ax25_dev *ax25_dev, *fwd_dev;
>
> - if ((ax25_dev = ax25_addr_ax25dev(&fwd->port_from)) == NULL)
> + ax25_dev = ax25_addr_ax25dev(&fwd->port_from);
> + if (ax25_dev == NULL) {
> + ax25_dev_put(ax25_dev);
NULL dereference.
> return -EINVAL;
> + }
>
> switch (cmd) {
> case SIOCAX25ADDFWD:
> - if ((fwd_dev = ax25_addr_ax25dev(&fwd->port_to)) == NULL)
> + fwd_dev = ax25_addr_ax25dev(&fwd->port_to);
> + if (fwd_dev == NULL) {
> + ax25_dev_put(fwd_dev);
NULL dereference.
> + ax25_dev_put(ax25_dev);
> return -EINVAL;
> - if (ax25_dev->forward != NULL)
> + }
> + if (ax25_dev->forward != NULL) {
> + ax25_dev_put(ax25_dev);
Drop the fwd_dev reference as well.
> return -EINVAL;
> + }
> ax25_dev->forward = fwd_dev->dev;
> + ax25_dev_put(fwd_dev);
> + ax25_dev_put(ax25_dev);
> break;
>
> case SIOCAX25DELFWD:
> - if (ax25_dev->forward == NULL)
> + if (ax25_dev->forward == NULL) {
> + ax25_dev_put(ax25_dev);
> return -EINVAL;
> + }
> ax25_dev->forward = NULL;
> + ax25_dev_put(ax25_dev);
> break;
>
> default:
> + ax25_dev_put(ax25_dev);
> return -EINVAL;
> }
>
> diff --git a/net/ax25/ax25_route.c b/net/ax25/ax25_route.c
> index d0b2e094bd5..7fe7a83b2a3 100644
> --- a/net/ax25/ax25_route.c
> +++ b/net/ax25/ax25_route.c
> @@ -75,10 +75,15 @@ static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
> ax25_dev *ax25_dev;
> int i;
>
> - if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
> + ax25_dev = ax25_addr_ax25dev(&route->port_addr);
> + if (ax25_dev == NULL) {
> + ax25_dev_put(ax25_dev);
NULL dereference.
> return -EINVAL;
> - if (route->digi_count > AX25_MAX_DIGIS)
> + }
> + if (route->digi_count > AX25_MAX_DIGIS) {
> + ax25_dev_put(ax25_dev);
> return -EINVAL;
> + }
>
> write_lock_bh(&ax25_route_lock);
>
> @@ -91,6 +96,7 @@ static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
> if (route->digi_count != 0) {
> if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
> write_unlock_bh(&ax25_route_lock);
> + ax25_dev_put(ax25_dev);
> return -ENOMEM;
> }
> ax25_rt->digipeat->lastrepeat = -1;
> @@ -101,6 +107,7 @@ static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
> }
> }
> write_unlock_bh(&ax25_route_lock);
> + ax25_dev_put(ax25_dev);
> return 0;
> }
> ax25_rt = ax25_rt->next;
> @@ -108,6 +115,7 @@ static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
>
> if ((ax25_rt = kmalloc(sizeof(ax25_route), GFP_ATOMIC)) == NULL) {
> write_unlock_bh(&ax25_route_lock);
> + ax25_dev_put(ax25_dev);
> return -ENOMEM;
> }
>
> @@ -120,6 +128,7 @@ static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
> if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
> write_unlock_bh(&ax25_route_lock);
> kfree(ax25_rt);
> + ax25_dev_put(ax25_dev);
> return -ENOMEM;
> }
> ax25_rt->digipeat->lastrepeat = -1;
> @@ -132,6 +141,7 @@ static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
> ax25_rt->next = ax25_route_list;
> ax25_route_list = ax25_rt;
> write_unlock_bh(&ax25_route_lock);
> + ax25_dev_put(ax25_dev);
>
> return 0;
> }
> @@ -147,8 +157,11 @@ static int ax25_rt_del(struct ax25_routes_struct *route)
> ax25_route *s, *t, *ax25_rt;
> ax25_dev *ax25_dev;
>
> - if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
> + ax25_dev = ax25_addr_ax25dev(&route->port_addr);
> + if (ax25_dev == NULL) {
> + ax25_dev_put(ax25_dev);
NULL dereference.
> return -EINVAL;
> + }
>
> write_lock_bh(&ax25_route_lock);
>
> @@ -173,7 +186,7 @@ static int ax25_rt_del(struct ax25_routes_struct *route)
> }
> }
> write_unlock_bh(&ax25_route_lock);
> -
> + ax25_dev_put(ax25_dev);
> return 0;
> }
>
> @@ -183,8 +196,11 @@ static int ax25_rt_opt(struct ax25_route_opt_struct *rt_option)
> ax25_dev *ax25_dev;
> int err = 0;
>
> - if ((ax25_dev = ax25_addr_ax25dev(&rt_option->port_addr)) == NULL)
> + ax25_dev = ax25_addr_ax25dev(&rt_option->port_addr);
> + if (ax25_dev == NULL) {
> + ax25_dev_put(ax25_dev);
NULL dereference.
> return -EINVAL;
> + }
>
> write_lock_bh(&ax25_route_lock);
>
> @@ -215,6 +231,7 @@ static int ax25_rt_opt(struct ax25_route_opt_struct *rt_option)
>
> out:
> write_unlock_bh(&ax25_route_lock);
> + ax25_dev_put(ax25_dev);
> return err;
> }
Thanks for this, but please can you resend with the above issues fixed
and based on top of net-next.
regards,
dan carpenter
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