Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 323 insertions, 0 deletions

diff --git a/lib/textsearch.c b/lib/textsearch.c
new file mode 100644
index 000000000..f68dea880
--- /dev/null
+++ b/lib/textsearch.c
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * lib/textsearch.c	Generic text search interface
+ *
+ * Authors:	Thomas Graf <tgraf@suug.ch>
+ * 		Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * ==========================================================================
+ */
+
+/**
+ * DOC: ts_intro
+ * INTRODUCTION
+ *
+ *   The textsearch infrastructure provides text searching facilities for
+ *   both linear and non-linear data. Individual search algorithms are
+ *   implemented in modules and chosen by the user.
+ *
+ * ARCHITECTURE
+ *
+ * .. code-block:: none
+ *
+ *     User
+ *     +----------------+
+ *     |        finish()|<--------------(6)-----------------+
+ *     |get_next_block()|<--------------(5)---------------+ |
+ *     |                |                     Algorithm   | |
+ *     |                |                    +------------------------------+
+ *     |                |                    |  init()   find()   destroy() |
+ *     |                |                    +------------------------------+
+ *     |                |       Core API           ^       ^          ^
+ *     |                |      +---------------+  (2)     (4)        (8)
+ *     |             (1)|----->| prepare()     |---+       |          |
+ *     |             (3)|----->| find()/next() |-----------+          |
+ *     |             (7)|----->| destroy()     |----------------------+
+ *     +----------------+      +---------------+
+ *
+ *   (1) User configures a search by calling textsearch_prepare() specifying
+ *       the search parameters such as the pattern and algorithm name.
+ *   (2) Core requests the algorithm to allocate and initialize a search
+ *       configuration according to the specified parameters.
+ *   (3) User starts the search(es) by calling textsearch_find() or
+ *       textsearch_next() to fetch subsequent occurrences. A state variable
+ *       is provided to the algorithm to store persistent variables.
+ *   (4) Core eventually resets the search offset and forwards the find()
+ *       request to the algorithm.
+ *   (5) Algorithm calls get_next_block() provided by the user continuously
+ *       to fetch the data to be searched in block by block.
+ *   (6) Algorithm invokes finish() after the last call to get_next_block
+ *       to clean up any leftovers from get_next_block. (Optional)
+ *   (7) User destroys the configuration by calling textsearch_destroy().
+ *   (8) Core notifies the algorithm to destroy algorithm specific
+ *       allocations. (Optional)
+ *
+ * USAGE
+ *
+ *   Before a search can be performed, a configuration must be created
+ *   by calling textsearch_prepare() specifying the searching algorithm,
+ *   the pattern to look for and flags. As a flag, you can set TS_IGNORECASE
+ *   to perform case insensitive matching. But it might slow down
+ *   performance of algorithm, so you should use it at own your risk.
+ *   The returned configuration may then be used for an arbitrary
+ *   amount of times and even in parallel as long as a separate struct
+ *   ts_state variable is provided to every instance.
+ *
+ *   The actual search is performed by either calling
+ *   textsearch_find_continuous() for linear data or by providing
+ *   an own get_next_block() implementation and
+ *   calling textsearch_find(). Both functions return
+ *   the position of the first occurrence of the pattern or UINT_MAX if
+ *   no match was found. Subsequent occurrences can be found by calling
+ *   textsearch_next() regardless of the linearity of the data.
+ *
+ *   Once you're done using a configuration it must be given back via
+ *   textsearch_destroy.
+ *
+ * EXAMPLE::
+ *
+ *   int pos;
+ *   struct ts_config *conf;
+ *   struct ts_state state;
+ *   const char *pattern = "chicken";
+ *   const char *example = "We dance the funky chicken";
+ *
+ *   conf = textsearch_prepare("kmp", pattern, strlen(pattern),
+ *                             GFP_KERNEL, TS_AUTOLOAD);
+ *   if (IS_ERR(conf)) {
+ *       err = PTR_ERR(conf);
+ *       goto errout;
+ *   }
+ *
+ *   pos = textsearch_find_continuous(conf, &state, example, strlen(example));
+ *   if (pos != UINT_MAX)
+ *       panic("Oh my god, dancing chickens at %d\n", pos);
+ *
+ *   textsearch_destroy(conf);
+ */
+/* ========================================================================== */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/err.h>
+#include <linux/textsearch.h>
+#include <linux/slab.h>
+
+static LIST_HEAD(ts_ops);
+static DEFINE_SPINLOCK(ts_mod_lock);
+
+static inline struct ts_ops *lookup_ts_algo(const char *name)
+{
+	struct ts_ops *o;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(o, &ts_ops, list) {
+		if (!strcmp(name, o->name)) {
+			if (!try_module_get(o->owner))
+				o = NULL;
+			rcu_read_unlock();
+			return o;
+		}
+	}
+	rcu_read_unlock();
+
+	return NULL;
+}
+
+/**
+ * textsearch_register - register a textsearch module
+ * @ops: operations lookup table
+ *
+ * This function must be called by textsearch modules to announce
+ * their presence. The specified &@ops must have %name set to a
+ * unique identifier and the callbacks find(), init(), get_pattern(),
+ * and get_pattern_len() must be implemented.
+ *
+ * Returns 0 or -EEXISTS if another module has already registered
+ * with same name.
+ */
+int textsearch_register(struct ts_ops *ops)
+{
+	int err = -EEXIST;
+	struct ts_ops *o;
+
+	if (ops->name == NULL || ops->find == NULL || ops->init == NULL ||
+	    ops->get_pattern == NULL || ops->get_pattern_len == NULL)
+		return -EINVAL;
+
+	spin_lock(&ts_mod_lock);
+	list_for_each_entry(o, &ts_ops, list) {
+		if (!strcmp(ops->name, o->name))
+			goto errout;
+	}
+
+	list_add_tail_rcu(&ops->list, &ts_ops);
+	err = 0;
+errout:
+	spin_unlock(&ts_mod_lock);
+	return err;
+}
+EXPORT_SYMBOL(textsearch_register);
+
+/**
+ * textsearch_unregister - unregister a textsearch module
+ * @ops: operations lookup table
+ *
+ * This function must be called by textsearch modules to announce
+ * their disappearance for examples when the module gets unloaded.
+ * The &ops parameter must be the same as the one during the
+ * registration.
+ *
+ * Returns 0 on success or -ENOENT if no matching textsearch
+ * registration was found.
+ */
+int textsearch_unregister(struct ts_ops *ops)
+{
+	int err = 0;
+	struct ts_ops *o;
+
+	spin_lock(&ts_mod_lock);
+	list_for_each_entry(o, &ts_ops, list) {
+		if (o == ops) {
+			list_del_rcu(&o->list);
+			goto out;
+		}
+	}
+
+	err = -ENOENT;
+out:
+	spin_unlock(&ts_mod_lock);
+	return err;
+}
+EXPORT_SYMBOL(textsearch_unregister);
+
+struct ts_linear_state
+{
+	unsigned int	len;
+	const void	*data;
+};
+
+static unsigned int get_linear_data(unsigned int consumed, const u8 **dst,
+				    struct ts_config *conf,
+				    struct ts_state *state)
+{
+	struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
+
+	if (likely(consumed < st->len)) {
+		*dst = st->data + consumed;
+		return st->len - consumed;
+	}
+
+	return 0;
+}
+
+/**
+ * textsearch_find_continuous - search a pattern in continuous/linear data
+ * @conf: search configuration
+ * @state: search state
+ * @data: data to search in
+ * @len: length of data
+ *
+ * A simplified version of textsearch_find() for continuous/linear data.
+ * Call textsearch_next() to retrieve subsequent matches.
+ *
+ * Returns the position of first occurrence of the pattern or
+ * %UINT_MAX if no occurrence was found.
+ */
+unsigned int textsearch_find_continuous(struct ts_config *conf,
+					struct ts_state *state,
+					const void *data, unsigned int len)
+{
+	struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
+
+	conf->get_next_block = get_linear_data;
+	st->data = data;
+	st->len = len;
+
+	return textsearch_find(conf, state);
+}
+EXPORT_SYMBOL(textsearch_find_continuous);
+
+/**
+ * textsearch_prepare - Prepare a search
+ * @algo: name of search algorithm
+ * @pattern: pattern data
+ * @len: length of pattern
+ * @gfp_mask: allocation mask
+ * @flags: search flags
+ *
+ * Looks up the search algorithm module and creates a new textsearch
+ * configuration for the specified pattern.
+ *
+ * Note: The format of the pattern may not be compatible between
+ *       the various search algorithms.
+ *
+ * Returns a new textsearch configuration according to the specified
+ * parameters or a ERR_PTR(). If a zero length pattern is passed, this
+ * function returns EINVAL.
+ */
+struct ts_config *textsearch_prepare(const char *algo, const void *pattern,
+				     unsigned int len, gfp_t gfp_mask, int flags)
+{
+	int err = -ENOENT;
+	struct ts_config *conf;
+	struct ts_ops *ops;
+	
+	if (len == 0)
+		return ERR_PTR(-EINVAL);
+
+	ops = lookup_ts_algo(algo);
+#ifdef CONFIG_MODULES
+	/*
+	 * Why not always autoload you may ask. Some users are
+	 * in a situation where requesting a module may deadlock,
+	 * especially when the module is located on a NFS mount.
+	 */
+	if (ops == NULL && flags & TS_AUTOLOAD) {
+		request_module("ts_%s", algo);
+		ops = lookup_ts_algo(algo);
+	}
+#endif
+
+	if (ops == NULL)
+		goto errout;
+
+	conf = ops->init(pattern, len, gfp_mask, flags);
+	if (IS_ERR(conf)) {
+		err = PTR_ERR(conf);
+		goto errout;
+	}
+
+	conf->ops = ops;
+	return conf;
+
+errout:
+	if (ops)
+		module_put(ops->owner);
+		
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL(textsearch_prepare);
+
+/**
+ * textsearch_destroy - destroy a search configuration
+ * @conf: search configuration
+ *
+ * Releases all references of the configuration and frees
+ * up the memory.
+ */
+void textsearch_destroy(struct ts_config *conf)
+{
+	if (conf->ops) {
+		if (conf->ops->destroy)
+			conf->ops->destroy(conf);
+		module_put(conf->ops->owner);
+	}
+
+	kfree(conf);
+}
+EXPORT_SYMBOL(textsearch_destroy);