This is a note to let you know that I've just added the patch titled

s390/qeth: fix double-free on IP add/remove race

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: s390-qeth-fix-double-free-on-ip-add-remove-race.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Tue Mar 6 19:02:12 PST 2018

From: Julian Wiedmann jwi@linux.vnet.ibm.com Date: Tue, 27 Feb 2018 18:58:14 +0100 Subject: s390/qeth: fix double-free on IP add/remove race

From: Julian Wiedmann jwi@linux.vnet.ibm.com

[ Upstream commit 14d066c3531a87f727968cacd85bd95c75f59843 ]

Registering an IPv4 address with the HW takes quite a while, so we temporarily drop the ip_htable lock. Any concurrent add/remove of the same IP adjusts the IP's use count, and (on remove) is then blocked by addr->in_progress. After the register call has completed, we check the use count for concurrently attempted add/remove calls - and possibly straight-away deregister the IP again. This happens via l3_delete_ip(), which 1) looks up the queried IP in the htable (getting a reference to the *same* queried object), 2) deregisters the IP from the HW, and 3) frees the IP object.

The caller in l3_add_ip() then does a second free on the same object.

For this case, skip all the extra checks and lookups in l3_delete_ip() and just deregister & free the IP object ourselves.

Fixes: 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback") Signed-off-by: Julian Wiedmann jwi@linux.vnet.ibm.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/s390/net/qeth_l3_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -319,7 +319,8 @@ int qeth_l3_add_ip(struct qeth_card *car (rc == IPA_RC_LAN_OFFLINE)) { addr->disp_flag = QETH_DISP_ADDR_DO_NOTHING; if (addr->ref_counter < 1) { - qeth_l3_delete_ip(card, addr); + qeth_l3_deregister_addr_entry(card, addr); + hash_del(&addr->hnode); kfree(addr); } } else {

Patches currently in stable-queue which might be from jwi@linux.vnet.ibm.com are

queue-4.14/s390-qeth-fix-setip-command-handling.patch queue-4.14/s390-qeth-fix-ip-address-lookup-for-l3-devices.patch queue-4.14/s390-qeth-fix-ipa-command-submission-race.patch queue-4.14/revert-s390-qeth-fix-using-of-ref-counter-for-rxip-addresses.patch queue-4.14/s390-qeth-fix-overestimated-count-of-buffer-elements.patch queue-4.14/s390-qeth-fix-double-free-on-ip-add-remove-race.patch queue-4.14/s390-qeth-fix-ip-removal-on-offline-cards.patch queue-4.14/s390-qeth-fix-underestimated-count-of-buffer-elements.patch