From: Michal Kubecek mkubecek@suse.cz
[ Upstream commit 365f9ae4ee36037e2a9268fe7296065356840b4c ]
If the genlmsg_put() call in ethnl_default_dumpit() fails, we bail out without checking if we already have some messages in current skb like we do with ethnl_default_dump_one() failure later. Therefore if existing messages almost fill up the buffer so that there is not enough space even for netlink and genetlink header, we lose all prepared messages and return and error.
Rather than duplicating the skb->len check, move the genlmsg_put(), genlmsg_cancel() and genlmsg_end() calls into ethnl_default_dump_one(). This is also more logical as all message composition will be in ethnl_default_dump_one() and only iteration logic will be left in ethnl_default_dumpit().
Fixes: 728480f12442 ("ethtool: default handlers for GET requests") Reported-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Michal Kubecek mkubecek@suse.cz Reviewed-by: Jakub Kicinski kuba@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ethtool/netlink.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-)
--- a/net/ethtool/netlink.c +++ b/net/ethtool/netlink.c @@ -376,10 +376,17 @@ err_dev: }
static int ethnl_default_dump_one(struct sk_buff *skb, struct net_device *dev, - const struct ethnl_dump_ctx *ctx) + const struct ethnl_dump_ctx *ctx, + struct netlink_callback *cb) { + void *ehdr; int ret;
+ ehdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq, + ðtool_genl_family, 0, ctx->ops->reply_cmd); + if (!ehdr) + return -EMSGSIZE; + ethnl_init_reply_data(ctx->reply_data, ctx->ops, dev); rtnl_lock(); ret = ctx->ops->prepare_data(ctx->req_info, ctx->reply_data, NULL); @@ -395,6 +402,10 @@ out: if (ctx->ops->cleanup_data) ctx->ops->cleanup_data(ctx->reply_data); ctx->reply_data->dev = NULL; + if (ret < 0) + genlmsg_cancel(skb, ehdr); + else + genlmsg_end(skb, ehdr); return ret; }
@@ -411,7 +422,6 @@ static int ethnl_default_dumpit(struct s int s_idx = ctx->pos_idx; int h, idx = 0; int ret = 0; - void *ehdr;
rtnl_lock(); for (h = ctx->pos_hash; h < NETDEV_HASHENTRIES; h++, s_idx = 0) { @@ -431,26 +441,15 @@ restart_chain: dev_hold(dev); rtnl_unlock();
- ehdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, - cb->nlh->nlmsg_seq, - ðtool_genl_family, 0, - ctx->ops->reply_cmd); - if (!ehdr) { - dev_put(dev); - ret = -EMSGSIZE; - goto out; - } - ret = ethnl_default_dump_one(skb, dev, ctx); + ret = ethnl_default_dump_one(skb, dev, ctx, cb); dev_put(dev); if (ret < 0) { - genlmsg_cancel(skb, ehdr); if (ret == -EOPNOTSUPP) goto lock_and_cont; if (likely(skb->len)) ret = skb->len; goto out; } - genlmsg_end(skb, ehdr); lock_and_cont: rtnl_lock(); if (net->dev_base_seq != seq) {