[PATCH 4.19 46/53] ax25: fix reference count leaks of ax25_dev

Greg Kroah-Hartman
2022-04-26T08:36:45Z

From: Duoming Zhou <duoming@zju.edu.cn>

commit 87563a043cef044fed5db7967a75741cc16ad2b1 upstream.

The previous commit d01ffb9eee4a ("ax25: add refcount in ax25_dev
to avoid UAF bugs") introduces refcount into ax25_dev, but there
are reference leak paths in ax25_ctl_ioctl(), ax25_fwd_ioctl(),
ax25_rt_add(), ax25_rt_del() and ax25_rt_opt().

This patch uses ax25_dev_put() and adjusts the position of
ax25_addr_ax25dev() to fix reference cout leaks of ax25_dev.

Fixes: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20220203150811.42256-1-duoming@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[OP: backport to 4.19: adjust context]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/ax25.h | 8 +++++---
net/ax25/af_ax25.c | 12 ++++++++----
net/ax25/ax25_dev.c | 24 +++++++++++++++++-------
net/ax25/ax25_route.c | 16 +++++++++++-----
4 files changed, 41 insertions(+), 19 deletions(-)

--- a/include/net/ax25.h
+++ b/include/net/ax25.h
@@ -291,10 +291,12 @@ static __inline__ void ax25_cb_put(ax25_
}
}

-#define ax25_dev_hold(__ax25_dev) \
- refcount_inc(&((__ax25_dev)->refcount))
+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)
+static inline void ax25_dev_put(ax25_dev *ax25_dev)
{
if (refcount_dec_and_test(&ax25_dev->refcount)) {
kfree(ax25_dev);
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -369,21 +369,25 @@ static int ax25_ctl_ioctl(const unsigned
if (copy_from_user(&ax25_ctl, arg, sizeof(ax25_ctl)))
return -EFAULT;

- if ((ax25_dev = ax25_addr_ax25dev(&ax25_ctl.port_addr)) == NULL)
- return -ENODEV;
-
if (ax25_ctl.digi_count > AX25_MAX_DIGIS)
return -EINVAL;

if (ax25_ctl.arg > ULONG_MAX / HZ && ax25_ctl.cmd != AX25_KILL)
return -EINVAL;

+ ax25_dev = ax25_addr_ax25dev(&ax25_ctl.port_addr);
+ if (!ax25_dev)
+ return -ENODEV;
+
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) {
+ ax25_dev_put(ax25_dev);
return -ENOTCONN;
+ }

switch (ax25_ctl.cmd) {
case AX25_KILL:
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -88,8 +88,8 @@ void ax25_dev_device_up(struct net_devic
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_dev_hold(ax25_dev);

ax25_register_dev_sysctl(ax25_dev);
}
@@ -118,8 +118,8 @@ void ax25_dev_device_down(struct net_dev

if ((s = ax25_dev_list) == ax25_dev) {
ax25_dev_list = s->next;
- ax25_dev_put(ax25_dev);
spin_unlock_bh(&ax25_dev_lock);
+ ax25_dev_put(ax25_dev);
dev->ax25_ptr = NULL;
dev_put(dev);
ax25_dev_put(ax25_dev);
@@ -129,8 +129,8 @@ void ax25_dev_device_down(struct net_dev
while (s != NULL && s->next != NULL) {
if (s->next == ax25_dev) {
s->next = ax25_dev->next;
- ax25_dev_put(ax25_dev);
spin_unlock_bh(&ax25_dev_lock);
+ ax25_dev_put(ax25_dev);
dev->ax25_ptr = NULL;
dev_put(dev);
ax25_dev_put(ax25_dev);
@@ -153,25 +153,35 @@ int ax25_fwd_ioctl(unsigned int cmd, str

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) {
+ ax25_dev_put(ax25_dev);
return -EINVAL;
- if (ax25_dev->forward != NULL)
+ }
+ if (ax25_dev->forward) {
+ ax25_dev_put(fwd_dev);
+ ax25_dev_put(ax25_dev);
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) {
+ 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;
}

- ax25_dev_put(ax25_dev);
return 0;
}

--- a/net/ax25/ax25_route.c
+++ b/net/ax25/ax25_route.c
@@ -78,11 +78,13 @@ static int __must_check ax25_rt_add(stru
ax25_dev *ax25_dev;
int i;

- if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
- return -EINVAL;
if (route->digi_count > AX25_MAX_DIGIS)
return -EINVAL;

+ ax25_dev = ax25_addr_ax25dev(&route->port_addr);
+ if (!ax25_dev)
+ return -EINVAL;
+
write_lock_bh(&ax25_route_lock);

ax25_rt = ax25_route_list;
@@ -94,6 +96,7 @@ static int __must_check ax25_rt_add(stru
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;
@@ -104,6 +107,7 @@ static int __must_check ax25_rt_add(stru
}
}
write_unlock_bh(&ax25_route_lock);
+ ax25_dev_put(ax25_dev);
return 0;
}
ax25_rt = ax25_rt->next;
@@ -111,6 +115,7 @@ static int __must_check ax25_rt_add(stru

if ((ax25_rt = kmalloc(sizeof(ax25_route), GFP_ATOMIC)) == NULL) {
write_unlock_bh(&ax25_route_lock);
+ ax25_dev_put(ax25_dev);
return -ENOMEM;
}

@@ -119,11 +124,11 @@ static int __must_check ax25_rt_add(stru
ax25_rt->dev = ax25_dev->dev;
ax25_rt->digipeat = NULL;
ax25_rt->ip_mode = ' ';
- ax25_dev_put(ax25_dev);
if (route->digi_count != 0) {
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;
@@ -136,6 +141,7 @@ static int __must_check ax25_rt_add(stru
ax25_rt->next = ax25_route_list;
ax25_route_list = ax25_rt;
write_unlock_bh(&ax25_route_lock);
+ ax25_dev_put(ax25_dev);

return 0;
}
@@ -176,8 +182,8 @@ static int ax25_rt_del(struct ax25_route
}
}
}
- ax25_dev_put(ax25_dev);
write_unlock_bh(&ax25_route_lock);
+ ax25_dev_put(ax25_dev);

return 0;
}
@@ -219,8 +225,8 @@ static int ax25_rt_opt(struct ax25_route
}

out:
- ax25_dev_put(ax25_dev);
write_unlock_bh(&ax25_route_lock);
+ ax25_dev_put(ax25_dev);
return err;
}