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| author | Duoming Zhou <duoming@zju.edu.cn> | 2022-04-21 13:24:15 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-27 13:39:45 +0200 |
| commit | e2b558fe507a1ed4c43db2b0057fc6e41f20a14c (patch) | |
| tree | 0c6822721b1acf6100f5e0131d8ba41a84e922f7 /include/net | |
| parent | ace51abe0f3a92d512440291f8a47e2cb094ca74 (diff) | |
| download | linux-stable-e2b558fe507a1ed4c43db2b0057fc6e41f20a14c.tar.gz linux-stable-e2b558fe507a1ed4c43db2b0057fc6e41f20a14c.tar.bz2 linux-stable-e2b558fe507a1ed4c43db2b0057fc6e41f20a14c.zip | |
ax25: add refcount in ax25_dev to avoid UAF bugs
commit d01ffb9eee4af165d83b08dd73ebdf9fe94a519b upstream.
If we dereference ax25_dev after we call kfree(ax25_dev) in
ax25_dev_device_down(), it will lead to concurrency UAF bugs.
There are eight syscall functions suffer from UAF bugs, include
ax25_bind(), ax25_release(), ax25_connect(), ax25_ioctl(),
ax25_getname(), ax25_sendmsg(), ax25_getsockopt() and
ax25_info_show().
One of the concurrency UAF can be shown as below:
(USE) | (FREE)
| ax25_device_event
| ax25_dev_device_down
ax25_bind | ...
... | kfree(ax25_dev)
ax25_fillin_cb() | ...
ax25_fillin_cb_from_dev() |
... |
The root cause of UAF bugs is that kfree(ax25_dev) in
ax25_dev_device_down() is not protected by any locks.
When ax25_dev, which there are still pointers point to,
is released, the concurrency UAF bug will happen.
This patch introduces refcount into ax25_dev in order to
guarantee that there are no pointers point to it when ax25_dev
is released.
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
[OP: backport to 4.19: adjusted context]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/ax25.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/net/ax25.h b/include/net/ax25.h index 8b7eb46ad72d..d81bfb674906 100644 --- a/include/net/ax25.h +++ b/include/net/ax25.h @@ -236,6 +236,7 @@ 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 { @@ -290,6 +291,15 @@ static __inline__ void ax25_cb_put(ax25_cb *ax25) } } +#define ax25_dev_hold(__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); + } +} static inline __be16 ax25_type_trans(struct sk_buff *skb, struct net_device *dev) { skb->dev = dev; |