From: Lin Ma <linma@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Xu Jia <xujia39@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>
---
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/3e0588c291d6ce225f2b891753ca41d45ba42469
[2] https://github.com/torvalds/linux/commit/b2f37aead1b82a770c48b5d583f35ec22aabb61e
[3] https://github.com/torvalds/linux/commit/0b9111922b1f399aba6ed1e1b8f2079c3da1aed8
[4] https://github.com/torvalds/linux/commit/81b1d548d00bcd028303c4f3150fa753b9b8aa71
Commits [1] and [2] are already present in 5.4-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 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. */
--
2.36.0
