This is a note to let you know that I've just added the patch titled net: x25: Increase refcnt of "struct x25_neigh" in x25_rx_call_request to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-x25-increase-refcnt-of-struct-x25_neigh-in-x25_rx_call_request.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sun Nov 22 12:12:04 PM CET 2020 From: Xie He <xie.he.0141@xxxxxxxxx> Date: Thu, 12 Nov 2020 02:35:06 -0800 Subject: net: x25: Increase refcnt of "struct x25_neigh" in x25_rx_call_request From: Xie He <xie.he.0141@xxxxxxxxx> [ Upstream commit 4ee18c179e5e815fa5575e0d2db0c05795a804ee ] The x25_disconnect function in x25_subr.c would decrease the refcount of "x25->neighbour" (struct x25_neigh) and reset this pointer to NULL. However, the x25_rx_call_request function in af_x25.c, which is called when we receive a connection request, does not increase the refcount when it assigns the pointer. Fix this issue by increasing the refcount of "struct x25_neigh" in x25_rx_call_request. This patch fixes frequent kernel crashes when using AF_X25 sockets. Fixes: 4becb7ee5b3d ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect") Cc: Martin Schiller <ms@xxxxxxxxxx> Signed-off-by: Xie He <xie.he.0141@xxxxxxxxx> Link: https://lore.kernel.org/r/20201112103506.5875-1-xie.he.0141@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/x25/af_x25.c | 1 + 1 file changed, 1 insertion(+) --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -1047,6 +1047,7 @@ int x25_rx_call_request(struct sk_buff * makex25->lci = lci; makex25->dest_addr = dest_addr; makex25->source_addr = source_addr; + x25_neigh_hold(nb); makex25->neighbour = nb; makex25->facilities = facilities; makex25->dte_facilities= dte_facilities; Patches currently in stable-queue which might be from xie.he.0141@xxxxxxxxx are queue-4.9/net-x25-increase-refcnt-of-struct-x25_neigh-in-x25_rx_call_request.patch