From 86e670f41afd3199699339393740a7c401fb26f1 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 15 Mar 2019 16:33:18 +0200 Subject: backports: genetlink: avoid NULL dereference If we fail to allocate extack, we fall back to the code path that tries to send an error *with* extack, but that will access our extack pointer. It also doesn't make sense, so just return an error back to netlink immediately and let it handle sending the error message to userspace. Signed-off-by: Johannes Berg Signed-off-by: Luca Coelho --- backport/compat/backport-genetlink.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/backport/compat/backport-genetlink.c b/backport/compat/backport-genetlink.c index 71bf45ad..885f1756 100644 --- a/backport/compat/backport-genetlink.c +++ b/backport/compat/backport-genetlink.c @@ -157,12 +157,10 @@ static int backport_pre_doit(__genl_const struct genl_ops *ops, #if LINUX_VERSION_IS_LESS(4,12,0) struct netlink_ext_ack *extack = kzalloc(sizeof(*extack), GFP_KERNEL); - __bp_genl_info_userhdr_set(info, extack); + if (!extack) + return -ENOMEM; - if (!extack) { - err = -ENOMEM; - goto err; - } + __bp_genl_info_userhdr_set(info, extack); extack->__bp_doit = ops->doit; #else @@ -175,7 +173,6 @@ static int backport_pre_doit(__genl_const struct genl_ops *ops, err = family->pre_doit(ops, skb, info); #if LINUX_VERSION_IS_LESS(4,12,0) -err: if (err) { /* signal to do nothing */ extack->__bp_doit = NULL; -- cgit v1.2.3