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authorLin Ma <linma@zju.edu.cn>2021-11-08 18:37:59 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-05-09 09:03:20 +0200
commit7361a35bf33064da203e521357acc4fccb8927e5 (patch)
tree7473a2626dd0805d37ce10f86795b9aa9b42ca2c /drivers
parent7dea5913000c6a2974a00d9af8e7ffb54e47eac1 (diff)
hamradio: defer 6pack kfree after unregister_netdev
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: Ovidiu Panait <ovidiu.panait@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/hamradio/6pack.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index 02d6f3ad9aca..82507a688efe 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -679,9 +679,11 @@ 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. */