ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 297 insertions, 0 deletions

diff --git a/net/ethtool/features.c b/net/ethtool/features.c
new file mode 100644
index 000000000..d9455b30a
--- /dev/null
+++ b/net/ethtool/features.c
@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <net/netdev_lock.h>
+
+#include "bitset.h"
+#include "common.h"
+#include "netlink.h"
+
+struct features_req_info {
+	struct ethnl_req_info	base;
+};
+
+struct features_reply_data {
+	struct ethnl_reply_data	base;
+	u32			hw[ETHTOOL_DEV_FEATURE_WORDS];
+	u32			wanted[ETHTOOL_DEV_FEATURE_WORDS];
+	u32			active[ETHTOOL_DEV_FEATURE_WORDS];
+	u32			nochange[ETHTOOL_DEV_FEATURE_WORDS];
+	u32			all[ETHTOOL_DEV_FEATURE_WORDS];
+};
+
+#define FEATURES_REPDATA(__reply_base) \
+	container_of(__reply_base, struct features_reply_data, base)
+
+const struct nla_policy ethnl_features_get_policy[] = {
+	[ETHTOOL_A_FEATURES_HEADER]	=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+};
+
+static void ethnl_features_to_bitmap32(u32 *dest, netdev_features_t src)
+{
+	unsigned int i;
+
+	for (i = 0; i < ETHTOOL_DEV_FEATURE_WORDS; i++)
+		dest[i] = src >> (32 * i);
+}
+
+static int features_prepare_data(const struct ethnl_req_info *req_base,
+				 struct ethnl_reply_data *reply_base,
+				 const struct genl_info *info)
+{
+	struct features_reply_data *data = FEATURES_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	netdev_features_t all_features;
+
+	ethnl_features_to_bitmap32(data->hw, dev->hw_features);
+	ethnl_features_to_bitmap32(data->wanted, dev->wanted_features);
+	ethnl_features_to_bitmap32(data->active, dev->features);
+	ethnl_features_to_bitmap32(data->nochange, NETIF_F_NEVER_CHANGE);
+	all_features = GENMASK_ULL(NETDEV_FEATURE_COUNT - 1, 0);
+	ethnl_features_to_bitmap32(data->all, all_features);
+
+	return 0;
+}
+
+static int features_reply_size(const struct ethnl_req_info *req_base,
+			       const struct ethnl_reply_data *reply_base)
+{
+	const struct features_reply_data *data = FEATURES_REPDATA(reply_base);
+	bool compact = req_base->flags & ETHTOOL_FLAG_COMPACT_BITSETS;
+	unsigned int len = 0;
+	int ret;
+
+	ret = ethnl_bitset32_size(data->hw, data->all, NETDEV_FEATURE_COUNT,
+				  netdev_features_strings, compact);
+	if (ret < 0)
+		return ret;
+	len += ret;
+	ret = ethnl_bitset32_size(data->wanted, NULL, NETDEV_FEATURE_COUNT,
+				  netdev_features_strings, compact);
+	if (ret < 0)
+		return ret;
+	len += ret;
+	ret = ethnl_bitset32_size(data->active, NULL, NETDEV_FEATURE_COUNT,
+				  netdev_features_strings, compact);
+	if (ret < 0)
+		return ret;
+	len += ret;
+	ret = ethnl_bitset32_size(data->nochange, NULL, NETDEV_FEATURE_COUNT,
+				  netdev_features_strings, compact);
+	if (ret < 0)
+		return ret;
+	len += ret;
+
+	return len;
+}
+
+static int features_fill_reply(struct sk_buff *skb,
+			       const struct ethnl_req_info *req_base,
+			       const struct ethnl_reply_data *reply_base)
+{
+	const struct features_reply_data *data = FEATURES_REPDATA(reply_base);
+	bool compact = req_base->flags & ETHTOOL_FLAG_COMPACT_BITSETS;
+	int ret;
+
+	ret = ethnl_put_bitset32(skb, ETHTOOL_A_FEATURES_HW, data->hw,
+				 data->all, NETDEV_FEATURE_COUNT,
+				 netdev_features_strings, compact);
+	if (ret < 0)
+		return ret;
+	ret = ethnl_put_bitset32(skb, ETHTOOL_A_FEATURES_WANTED, data->wanted,
+				 NULL, NETDEV_FEATURE_COUNT,
+				 netdev_features_strings, compact);
+	if (ret < 0)
+		return ret;
+	ret = ethnl_put_bitset32(skb, ETHTOOL_A_FEATURES_ACTIVE, data->active,
+				 NULL, NETDEV_FEATURE_COUNT,
+				 netdev_features_strings, compact);
+	if (ret < 0)
+		return ret;
+	return ethnl_put_bitset32(skb, ETHTOOL_A_FEATURES_NOCHANGE,
+				  data->nochange, NULL, NETDEV_FEATURE_COUNT,
+				  netdev_features_strings, compact);
+}
+
+const struct ethnl_request_ops ethnl_features_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_FEATURES_GET,
+	.reply_cmd		= ETHTOOL_MSG_FEATURES_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_FEATURES_HEADER,
+	.req_info_size		= sizeof(struct features_req_info),
+	.reply_data_size	= sizeof(struct features_reply_data),
+
+	.prepare_data		= features_prepare_data,
+	.reply_size		= features_reply_size,
+	.fill_reply		= features_fill_reply,
+};
+
+/* FEATURES_SET */
+
+const struct nla_policy ethnl_features_set_policy[] = {
+	[ETHTOOL_A_FEATURES_HEADER]	=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+	[ETHTOOL_A_FEATURES_WANTED]	= { .type = NLA_NESTED },
+};
+
+static void ethnl_features_to_bitmap(unsigned long *dest, netdev_features_t val)
+{
+	const unsigned int words = BITS_TO_LONGS(NETDEV_FEATURE_COUNT);
+	unsigned int i;
+
+	for (i = 0; i < words; i++)
+		dest[i] = (unsigned long)(val >> (i * BITS_PER_LONG));
+}
+
+static netdev_features_t ethnl_bitmap_to_features(unsigned long *src)
+{
+	const unsigned int nft_bits = sizeof(netdev_features_t) * BITS_PER_BYTE;
+	const unsigned int words = BITS_TO_LONGS(NETDEV_FEATURE_COUNT);
+	netdev_features_t ret = 0;
+	unsigned int i;
+
+	for (i = 0; i < words; i++)
+		ret |= (netdev_features_t)(src[i]) << (i * BITS_PER_LONG);
+	ret &= ~(netdev_features_t)0 >> (nft_bits - NETDEV_FEATURE_COUNT);
+	return ret;
+}
+
+static int features_send_reply(struct net_device *dev, struct genl_info *info,
+			       const unsigned long *wanted,
+			       const unsigned long *wanted_mask,
+			       const unsigned long *active,
+			       const unsigned long *active_mask, bool compact)
+{
+	struct sk_buff *rskb;
+	void *reply_payload;
+	int reply_len = 0;
+	int ret;
+
+	reply_len = ethnl_reply_header_size();
+	ret = ethnl_bitset_size(wanted, wanted_mask, NETDEV_FEATURE_COUNT,
+				netdev_features_strings, compact);
+	if (ret < 0)
+		goto err;
+	reply_len += ret;
+	ret = ethnl_bitset_size(active, active_mask, NETDEV_FEATURE_COUNT,
+				netdev_features_strings, compact);
+	if (ret < 0)
+		goto err;
+	reply_len += ret;
+
+	ret = -ENOMEM;
+	rskb = ethnl_reply_init(reply_len, dev, ETHTOOL_MSG_FEATURES_SET_REPLY,
+				ETHTOOL_A_FEATURES_HEADER, info,
+				&reply_payload);
+	if (!rskb)
+		goto err;
+
+	ret = ethnl_put_bitset(rskb, ETHTOOL_A_FEATURES_WANTED, wanted,
+			       wanted_mask, NETDEV_FEATURE_COUNT,
+			       netdev_features_strings, compact);
+	if (ret < 0)
+		goto nla_put_failure;
+	ret = ethnl_put_bitset(rskb, ETHTOOL_A_FEATURES_ACTIVE, active,
+			       active_mask, NETDEV_FEATURE_COUNT,
+			       netdev_features_strings, compact);
+	if (ret < 0)
+		goto nla_put_failure;
+
+	genlmsg_end(rskb, reply_payload);
+	ret = genlmsg_reply(rskb, info);
+	return ret;
+
+nla_put_failure:
+	nlmsg_free(rskb);
+	WARN_ONCE(1, "calculated message payload length (%d) not sufficient\n",
+		  reply_len);
+err:
+	GENL_SET_ERR_MSG(info, "failed to send reply message");
+	return ret;
+}
+
+int ethnl_set_features(struct sk_buff *skb, struct genl_info *info)
+{
+	DECLARE_BITMAP(wanted_diff_mask, NETDEV_FEATURE_COUNT);
+	DECLARE_BITMAP(active_diff_mask, NETDEV_FEATURE_COUNT);
+	DECLARE_BITMAP(old_active, NETDEV_FEATURE_COUNT);
+	DECLARE_BITMAP(old_wanted, NETDEV_FEATURE_COUNT);
+	DECLARE_BITMAP(new_active, NETDEV_FEATURE_COUNT);
+	DECLARE_BITMAP(new_wanted, NETDEV_FEATURE_COUNT);
+	DECLARE_BITMAP(req_wanted, NETDEV_FEATURE_COUNT);
+	DECLARE_BITMAP(req_mask, NETDEV_FEATURE_COUNT);
+	struct ethnl_req_info req_info = {};
+	struct nlattr **tb = info->attrs;
+	struct net_device *dev;
+	bool mod;
+	int ret;
+
+	if (!tb[ETHTOOL_A_FEATURES_WANTED])
+		return -EINVAL;
+	ret = ethnl_parse_header_dev_get(&req_info,
+					 tb[ETHTOOL_A_FEATURES_HEADER],
+					 genl_info_net(info), info->extack,
+					 true);
+	if (ret < 0)
+		return ret;
+	dev = req_info.dev;
+
+	rtnl_lock();
+	netdev_lock_ops(dev);
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		goto out_unlock;
+	ethnl_features_to_bitmap(old_active, dev->features);
+	ethnl_features_to_bitmap(old_wanted, dev->wanted_features);
+	ret = ethnl_parse_bitset(req_wanted, req_mask, NETDEV_FEATURE_COUNT,
+				 tb[ETHTOOL_A_FEATURES_WANTED],
+				 netdev_features_strings, info->extack);
+	if (ret < 0)
+		goto out_ops;
+	if (ethnl_bitmap_to_features(req_mask) & ~NETIF_F_ETHTOOL_BITS) {
+		GENL_SET_ERR_MSG(info, "attempt to change non-ethtool features");
+		ret = -EINVAL;
+		goto out_ops;
+	}
+
+	/* set req_wanted bits not in req_mask from old_wanted */
+	bitmap_and(req_wanted, req_wanted, req_mask, NETDEV_FEATURE_COUNT);
+	bitmap_andnot(new_wanted, old_wanted, req_mask, NETDEV_FEATURE_COUNT);
+	bitmap_or(req_wanted, new_wanted, req_wanted, NETDEV_FEATURE_COUNT);
+	if (!bitmap_equal(req_wanted, old_wanted, NETDEV_FEATURE_COUNT)) {
+		dev->wanted_features &= ~dev->hw_features;
+		dev->wanted_features |= ethnl_bitmap_to_features(req_wanted) & dev->hw_features;
+		__netdev_update_features(dev);
+	}
+	ethnl_features_to_bitmap(new_active, dev->features);
+	mod = !bitmap_equal(old_active, new_active, NETDEV_FEATURE_COUNT);
+
+	ret = 0;
+	if (!(req_info.flags & ETHTOOL_FLAG_OMIT_REPLY)) {
+		bool compact = req_info.flags & ETHTOOL_FLAG_COMPACT_BITSETS;
+
+		bitmap_xor(wanted_diff_mask, req_wanted, new_active,
+			   NETDEV_FEATURE_COUNT);
+		bitmap_xor(active_diff_mask, old_active, new_active,
+			   NETDEV_FEATURE_COUNT);
+		bitmap_and(wanted_diff_mask, wanted_diff_mask, req_mask,
+			   NETDEV_FEATURE_COUNT);
+		bitmap_and(req_wanted, req_wanted, wanted_diff_mask,
+			   NETDEV_FEATURE_COUNT);
+		bitmap_and(new_active, new_active, active_diff_mask,
+			   NETDEV_FEATURE_COUNT);
+
+		ret = features_send_reply(dev, info, req_wanted,
+					  wanted_diff_mask, new_active,
+					  active_diff_mask, compact);
+	}
+	if (mod)
+		netdev_features_change(dev);
+
+out_ops:
+	ethnl_ops_complete(dev);
+out_unlock:
+	netdev_unlock_ops(dev);
+	rtnl_unlock();
+	ethnl_parse_header_dev_put(&req_info);
+	return ret;
+}