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authorLin Ma <linma@zju.edu.cn>2021-11-08 18:37:59 +0800
committerDavid S. Miller <davem@davemloft.net>2021-11-09 11:49:12 +0000
commit0b9111922b1f399aba6ed1e1b8f2079c3da1aed8 (patch)
tree170686756f3248243afccecb824ca94187b50809 /drivers/net/hamradio/6pack.c
parenthamradio: defer ax25 kfree after unregister_netdev (diff)
downloadlinux-dev-0b9111922b1f399aba6ed1e1b8f2079c3da1aed8.tar.xz
linux-dev-0b9111922b1f399aba6ed1e1b8f2079c3da1aed8.zip
hamradio: defer 6pack kfree after unregister_netdev
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>
Diffstat (limited to '')
-rw-r--r--drivers/net/hamradio/6pack.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index f4e8793e995d..fb0a3825edd0 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -672,11 +672,13 @@ 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. */
+ unregister_netdev(sp->dev);
+
+ /* Free all 6pack frame buffers after unreg. */
kfree(sp->rbuff);
kfree(sp->xbuff);
- unregister_netdev(sp->dev);
+ free_netdev(sp->dev);
}
/* Perform I/O control on an active 6pack channel. */