* [PATCH 4.14 1/2] hamradio: defer 6pack kfree after unregister_netdev
@ 2022-04-28 14:10 Ovidiu Panait
2022-04-28 14:10 ` [PATCH 4.14 2/2] hamradio: remove needs_free_netdev to avoid UAF Ovidiu Panait
0 siblings, 1 reply; 2+ messages in thread
From: Ovidiu Panait @ 2022-04-28 14:10 UTC (permalink / raw)
To: stable
Cc: Lin Ma, David S . Miller, Xu Jia, Greg Kroah-Hartman, Ovidiu Panait
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/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 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. */
--
2.36.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 4.14 2/2] hamradio: remove needs_free_netdev to avoid UAF
2022-04-28 14:10 [PATCH 4.14 1/2] hamradio: defer 6pack kfree after unregister_netdev Ovidiu Panait
@ 2022-04-28 14:10 ` Ovidiu Panait
0 siblings, 0 replies; 2+ messages in thread
From: Ovidiu Panait @ 2022-04-28 14:10 UTC (permalink / raw)
To: stable; +Cc: Lin Ma, Jakub Kicinski, Xu Jia, Greg Kroah-Hartman, Ovidiu Panait
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;
--
2.36.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-04-28 14:11 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-28 14:10 [PATCH 4.14 1/2] hamradio: defer 6pack kfree after unregister_netdev Ovidiu Panait
2022-04-28 14:10 ` [PATCH 4.14 2/2] hamradio: remove needs_free_netdev to avoid UAF Ovidiu Panait
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).