From: Lin Ma linma@zju.edu.cn
commit 0b9111922b1f399aba6ed1e1b8f2079c3da1aed8 upstream.
There is a possible race condition (use-after-free) like below
(USE) | (FREE) dev_queue_xmit | __dev_queue_xmit | __dev_xmit_skb | sch_direct_xmit | ... xmit_one | netdev_start_xmit | tty_ldisc_kill __netdev_start_xmit | 6pack_close sp_xmit | kfree sp_encaps | |
According to the patch "defer ax25 kfree after unregister_netdev", this patch reorder the kfree after the unregister_netdev to avoid the possible UAF as the unregister_netdev() is well synchronized and won't return if there is a running routine.
Signed-off-by: Lin Ma linma@zju.edu.cn Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Xu Jia xujia39@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- These commits are part of CVE-2022-1195 patchset. Reference: https://bugzilla.redhat.com/show_bug.cgi?id=2056381 [1] https://github.com/torvalds/linux/commit/3e0588c291d6ce225f2b891753ca41d45ba... [2] https://github.com/torvalds/linux/commit/b2f37aead1b82a770c48b5d583f35ec22aa... [3] https://github.com/torvalds/linux/commit/0b9111922b1f399aba6ed1e1b8f2079c3da... [4] https://github.com/torvalds/linux/commit/81b1d548d00bcd028303c4f3150fa753b9b...
Commits [1] and [2] are already present in 4.14-stable, this patchset includes backports for [3] and [4] (clean cherry-picks from 5.10 stable).
drivers/net/hamradio/6pack.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index 3d5b2b4899ec..7ff1c6f7eea2 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -690,9 +690,11 @@ static void sixpack_close(struct tty_struct *tty) del_timer_sync(&sp->tx_t); del_timer_sync(&sp->resync_t);
- /* Free all 6pack frame buffers. */ + /* Free all 6pack frame buffers after unreg. */ kfree(sp->rbuff); kfree(sp->xbuff); + + free_netdev(sp->dev); }
/* Perform I/O control on an active 6pack channel. */
From: Lin Ma linma@zju.edu.cn
commit 81b1d548d00bcd028303c4f3150fa753b9b8aa71 upstream.
The former patch "defer 6pack kfree after unregister_netdev" reorders the kfree of two buffer after the unregister_netdev to prevent the race condition. It also adds free_netdev() function in sixpack_close(), which is a direct copy from the similar code in mkiss_close().
However, in sixpack driver, the flag needs_free_netdev is set to true in sp_setup(), hence the unregister_netdev() will free the netdev automatically. Therefore, as the sp is netdev_priv, use-after-free occurs.
This patch removes the needs_free_netdev = true and just let the free_netdev to finish this deallocation task.
Fixes: 0b9111922b1f ("hamradio: defer 6pack kfree after unregister_netdev") Signed-off-by: Lin Ma linma@zju.edu.cn Link: https://lore.kernel.org/r/20211111141402.7551-1-linma@zju.edu.cn Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Xu Jia xujia39@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- drivers/net/hamradio/6pack.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index 7ff1c6f7eea2..2d239c014541 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -311,7 +311,6 @@ static void sp_setup(struct net_device *dev) { /* Finish setting up the DEVICE info. */ dev->netdev_ops = &sp_netdev_ops; - dev->needs_free_netdev = true; dev->mtu = SIXP_MTU; dev->hard_header_len = AX25_MAX_HEADER_LEN; dev->header_ops = &ax25_header_ops;
linux-stable-mirror@lists.linaro.org
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Ovidiu Panait