The first patch uses kernel universal linked list to implement
ax25_dev_list, which makes the operation of the list easier.
The second and third patch fix reference count leak issues of
the object "ax25_dev" and "net_device".
Duoming Zhou (3):
ax25: Use kernel universal linked list to implement ax25_dev_list
ax25: Fix reference count leak issues of ax25_dev
ax25: Fix reference count leak issue of net_device
include/net/ax25.h | 3 +--
net/ax25/ax25_dev.c | 48 +++++++++++++++------------------------------
2 files changed, 17 insertions(+), 34 deletions(-)
--
2.17.1
The origin ax25_dev_list implements its own single linked list,
which is complicated and error-prone. For example, when deleting
the node of ax25_dev_list in ax25_dev_device_down(), we have to
operate on the head node and other nodes separately.
This patch uses kernel universal linked list to replace original
ax25_dev_list, which make the operation of ax25_dev_list easier.
We should do "dev->ax25_ptr = ax25_dev;" and "dev->ax25_ptr = NULL;"
while holding the spinlock, otherwise the ax25_dev_device_up() and
ax25_dev_device_down() could race.
Suggested-by: Dan Carpenter <[email protected]>
Signed-off-by: Duoming Zhou <[email protected]>
---
include/net/ax25.h | 3 +--
net/ax25/ax25_dev.c | 40 +++++++++++++++-------------------------
2 files changed, 16 insertions(+), 27 deletions(-)
diff --git a/include/net/ax25.h b/include/net/ax25.h
index 0d939e5aee4..c2a85fd3f5e 100644
--- a/include/net/ax25.h
+++ b/include/net/ax25.h
@@ -216,7 +216,7 @@ typedef struct {
struct ctl_table;
typedef struct ax25_dev {
- struct ax25_dev *next;
+ struct list_head list;
struct net_device *dev;
netdevice_tracker dev_tracker;
@@ -330,7 +330,6 @@ int ax25_addr_size(const ax25_digi *);
void ax25_digi_invert(const ax25_digi *, ax25_digi *);
/* ax25_dev.c */
-extern ax25_dev *ax25_dev_list;
extern spinlock_t ax25_dev_lock;
#if IS_ENABLED(CONFIG_AX25)
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index 282ec581c07..f16ee5c09d0 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -22,11 +22,12 @@
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
+#include <linux/list.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/init.h>
-ax25_dev *ax25_dev_list;
+static LIST_HEAD(ax25_dev_list);
DEFINE_SPINLOCK(ax25_dev_lock);
ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
@@ -34,7 +35,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
ax25_dev *ax25_dev, *res = NULL;
spin_lock_bh(&ax25_dev_lock);
- for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
+ list_for_each_entry(ax25_dev, &ax25_dev_list, list)
if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
res = ax25_dev;
ax25_dev_hold(ax25_dev);
@@ -59,7 +60,6 @@ void ax25_dev_device_up(struct net_device *dev)
}
refcount_set(&ax25_dev->refcount, 1);
- dev->ax25_ptr = ax25_dev;
ax25_dev->dev = dev;
netdev_hold(dev, &ax25_dev->dev_tracker, GFP_KERNEL);
ax25_dev->forward = NULL;
@@ -85,8 +85,8 @@ void ax25_dev_device_up(struct net_device *dev)
#endif
spin_lock_bh(&ax25_dev_lock);
- ax25_dev->next = ax25_dev_list;
- ax25_dev_list = ax25_dev;
+ list_add(&ax25_dev->list, &ax25_dev_list);
+ dev->ax25_ptr = ax25_dev;
spin_unlock_bh(&ax25_dev_lock);
ax25_dev_hold(ax25_dev);
@@ -111,32 +111,25 @@ void ax25_dev_device_down(struct net_device *dev)
/*
* Remove any packet forwarding that points to this device.
*/
- for (s = ax25_dev_list; s != NULL; s = s->next)
+ list_for_each_entry(s, &ax25_dev_list, list)
if (s->forward == dev)
s->forward = NULL;
- if ((s = ax25_dev_list) == ax25_dev) {
- ax25_dev_list = s->next;
- goto unlock_put;
- }
-
- while (s != NULL && s->next != NULL) {
- if (s->next == ax25_dev) {
- s->next = ax25_dev->next;
+ list_for_each_entry(s, &ax25_dev_list, list) {
+ if (s == ax25_dev) {
+ list_del(&s->list);
goto unlock_put;
}
-
- s = s->next;
}
- spin_unlock_bh(&ax25_dev_lock);
dev->ax25_ptr = NULL;
+ spin_unlock_bh(&ax25_dev_lock);
ax25_dev_put(ax25_dev);
return;
unlock_put:
+ dev->ax25_ptr = NULL;
spin_unlock_bh(&ax25_dev_lock);
ax25_dev_put(ax25_dev);
- dev->ax25_ptr = NULL;
netdev_put(dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
}
@@ -200,16 +193,13 @@ struct net_device *ax25_fwd_dev(struct net_device *dev)
*/
void __exit ax25_dev_free(void)
{
- ax25_dev *s, *ax25_dev;
+ ax25_dev *s, *n;
spin_lock_bh(&ax25_dev_lock);
- ax25_dev = ax25_dev_list;
- while (ax25_dev != NULL) {
- s = ax25_dev;
- netdev_put(ax25_dev->dev, &ax25_dev->dev_tracker);
- ax25_dev = ax25_dev->next;
+ list_for_each_entry_safe(s, n, &ax25_dev_list, list) {
+ netdev_put(s->dev, &s->dev_tracker);
+ list_del(&s->list);
kfree(s);
}
- ax25_dev_list = NULL;
spin_unlock_bh(&ax25_dev_lock);
}
--
2.17.1
There is a reference count leak issue of the object "net_device" in
ax25_dev_device_down(). When the ax25 device is shutting down, the
ax25_dev_device_down() drops the reference count of net_device one
or zero times depending on if we goto unlock_put or not, which will
cause memory leak.
In order to solve the above issue, decrease the reference count of
net_device after dev->ax25_ptr is set to null.
Fixes: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs")
Suggested-by: Dan Carpenter <[email protected]>
Signed-off-by: Duoming Zhou <[email protected]>
---
net/ax25/ax25_dev.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index 52ccc37d568..c9d55b99a7a 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -118,15 +118,10 @@ void ax25_dev_device_down(struct net_device *dev)
list_for_each_entry(s, &ax25_dev_list, list) {
if (s == ax25_dev) {
list_del(&s->list);
- goto unlock_put;
+ break;
}
}
- dev->ax25_ptr = NULL;
- spin_unlock_bh(&ax25_dev_lock);
- ax25_dev_put(ax25_dev);
- return;
-unlock_put:
dev->ax25_ptr = NULL;
spin_unlock_bh(&ax25_dev_lock);
netdev_put(dev, &ax25_dev->dev_tracker);
--
2.17.1
The ax25_addr_ax25dev() and ax25_dev_device_down() exist a reference
count leak issue of the object "ax25_dev".
Memory leak issue in ax25_addr_ax25dev():
The reference count of the object "ax25_dev" can be increased multiple
times in ax25_addr_ax25dev(). This will cause a memory leak.
Memory leak issues in ax25_dev_device_down():
The reference count of ax25_dev is set to 1 in ax25_dev_device_up() and
then increase the reference count when ax25_dev is added to ax25_dev_list.
As a result, the reference count of ax25_dev is 2. But when the device is
shutting down. The ax25_dev_device_down() drops the reference count once
or twice depending on if we goto unlock_put or not, which will cause
memory leak.
As for the issue of ax25_addr_ax25dev(), it is impossible for one pointer
to be on a list twice. So add a break in ax25_addr_ax25dev(). As for the
issue of ax25_dev_device_down(), increase the reference count of ax25_dev
once in ax25_dev_device_up() and decrease the reference count of ax25_dev
after it is removed from the ax25_dev_list.
Fixes: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs")
Suggested-by: Dan Carpenter <[email protected]>
Signed-off-by: Duoming Zhou <[email protected]>
---
net/ax25/ax25_dev.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index f16ee5c09d0..52ccc37d568 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -39,6 +39,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
res = ax25_dev;
ax25_dev_hold(ax25_dev);
+ break;
}
spin_unlock_bh(&ax25_dev_lock);
@@ -88,7 +89,6 @@ void ax25_dev_device_up(struct net_device *dev)
list_add(&ax25_dev->list, &ax25_dev_list);
dev->ax25_ptr = ax25_dev;
spin_unlock_bh(&ax25_dev_lock);
- ax25_dev_hold(ax25_dev);
ax25_register_dev_sysctl(ax25_dev);
}
@@ -129,7 +129,6 @@ void ax25_dev_device_down(struct net_device *dev)
unlock_put:
dev->ax25_ptr = NULL;
spin_unlock_bh(&ax25_dev_lock);
- ax25_dev_put(ax25_dev);
netdev_put(dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
}
--
2.17.1
On Thu, May 09, 2024 at 05:35:59PM +0800, Duoming Zhou wrote:
> The first patch uses kernel universal linked list to implement
> ax25_dev_list, which makes the operation of the list easier.
> The second and third patch fix reference count leak issues of
> the object "ax25_dev" and "net_device".
>
> Duoming Zhou (3):
> ax25: Use kernel universal linked list to implement ax25_dev_list
> ax25: Fix reference count leak issues of ax25_dev
> ax25: Fix reference count leak issue of net_device
Reviewed-by: Dan Carpenter <[email protected]>
regards,
dan carpenter
Hello:
This series was applied to netdev/net.git (main)
by Jakub Kicinski <[email protected]>:
On Thu, 9 May 2024 17:35:59 +0800 you wrote:
> The first patch uses kernel universal linked list to implement
> ax25_dev_list, which makes the operation of the list easier.
> The second and third patch fix reference count leak issues of
> the object "ax25_dev" and "net_device".
>
> Duoming Zhou (3):
> ax25: Use kernel universal linked list to implement ax25_dev_list
> ax25: Fix reference count leak issues of ax25_dev
> ax25: Fix reference count leak issue of net_device
>
> [...]
Here is the summary with links:
- [net,v7,1/3] ax25: Use kernel universal linked list to implement ax25_dev_list
https://git.kernel.org/netdev/net/c/a7d6e36b9ad0
- [net,v7,2/3] ax25: Fix reference count leak issues of ax25_dev
https://git.kernel.org/netdev/net/c/b505e0319852
- [net,v7,3/3] ax25: Fix reference count leak issue of net_device
https://git.kernel.org/netdev/net/c/36e56b1b002b
You are awesome, thank you!
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