[PATCH 0/8] [GIT PULL] tracing: Minor clean ups, fixes and error checking

[PATCH 0/8] [GIT PULL] tracing: Minor clean ups, fixes and error checking

[Steven Rostedt]

Linus,

This contains a series of last minute clean ups, small fixes and
error checks.

Please pull the latest trace-v5.1-2 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v5.1-2

Tag SHA1: de3d34862ab43473fb0ce9d774c09241b85c7c9c
Head SHA1: a039480e9e93896cadc5a91468964febb3c5d488


Douglas Anderson (1):
      tracing: kdb: Fix ftdump to not sleep

Masami Hiramatsu (5):
      tracing/probe: Check maxactive error cases
      tracing/probe: Check event name length correctly
      tracing/probe: Check the size of argument name and body
      tracing/probe: Check event/group naming rule at parsing
      tracing/probe: Verify alloc_trace_*probe() result

Valdis Kletnieks (2):
      tracing/probes: Make reserved_field_names static
      trace/probes: Remove kernel doc style from non kernel doc comment

----
 include/linux/ring_buffer.h |  2 +-
 kernel/trace/ring_buffer.c  |  5 +++--
 kernel/trace/trace.c        |  6 ++++--
 kernel/trace/trace_kdb.c    |  6 ++++--
 kernel/trace/trace_kprobe.c | 23 +++++++++++------------
 kernel/trace/trace_probe.c  | 20 ++++++++++++++++++--
 kernel/trace/trace_probe.h  |  1 +
 kernel/trace/trace_uprobe.c |  8 +++-----
 8 files changed, 45 insertions(+), 26 deletions(-)

[PATCH 1/8] tracing/probes: Make reserved_field_names static

[Steven Rostedt]

From: =?UTF-8?q?Valdis=20Kl=C4=93tnieks?= <valdis.kletnieks@vt.edu>

sparse complains:
  CHECK   kernel/trace/trace_probe.c
kernel/trace/trace_probe.c:16:12: warning: symbol 'reserved_field_names' was not declared. Should it be static?

Yes, it should be static.

Link: http://lkml.kernel.org/r/2478.1552380778@turing-police

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 89da34b326e3..cfcf77e6fb19 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -13,7 +13,7 @@
 
 #include "trace_probe.h"
 
-const char *reserved_field_names[] = {
+static const char *reserved_field_names[] = {
 	"common_type",
 	"common_flags",
 	"common_preempt_count",
-- 
2.20.1

[PATCH 2/8] trace/probes: Remove kernel doc style from non kernel doc comment

[Steven Rostedt]

From: =?UTF-8?q?Valdis=20Kl=C4=93tnieks?= <valdis.kletnieks@vt.edu>

  CC      kernel/trace/trace_kprobe.o
kernel/trace/trace_kprobe.c:41: warning: cannot understand function prototype: 'struct trace_kprobe '

The real problem is that a comment looked like kerneldoc when it shouldn't be...

Link: http://lkml.kernel.org/r/2812.1552381112@turing-police

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_kprobe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d5fb09ebba8b..ceafa0a2b1d1 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -35,7 +35,7 @@ static struct dyn_event_operations trace_kprobe_ops = {
 	.match = trace_kprobe_match,
 };
 
-/**
+/*
  * Kprobe event core functions
  */
 struct trace_kprobe {
-- 
2.20.1

[PATCH 3/8] tracing: kdb: Fix ftdump to not sleep

[Steven Rostedt]

From: Douglas Anderson <dianders@chromium.org>

As reported back in 2016-11 [1], the "ftdump" kdb command triggers a
BUG for "sleeping function called from invalid context".

kdb's "ftdump" command wants to call ring_buffer_read_prepare() in
atomic context.  A very simple solution for this is to add allocation
flags to ring_buffer_read_prepare() so kdb can call it without
triggering the allocation error.  This patch does that.

Note that in the original email thread about this, it was suggested
that perhaps the solution for kdb was to either preallocate the buffer
ahead of time or create our own iterator.  I'm hoping that this
alternative of adding allocation flags to ring_buffer_read_prepare()
can be considered since it means I don't need to duplicate more of the
core trace code into "trace_kdb.c" (for either creating my own
iterator or re-preparing a ring allocator whose memory was already
allocated).

NOTE: another option for kdb is to actually figure out how to make it
reuse the existing ftrace_dump() function and totally eliminate the
duplication.  This sounds very appealing and actually works (the "sr
z" command can be seen to properly dump the ftrace buffer).  The
downside here is that ftrace_dump() fully consumes the trace buffer.
Unless that is changed I'd rather not use it because it means "ftdump
| grep xyz" won't be very useful to search the ftrace buffer since it
will throw away the whole trace on the first grep.  A future patch to
dump only the last few lines of the buffer will also be hard to
implement.

[1] https://lkml.kernel.org/r/20161117191605.GA21459@google.com

Link: http://lkml.kernel.org/r/20190308193205.213659-1-dianders@chromium.org

Reported-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/linux/ring_buffer.h | 2 +-
 kernel/trace/ring_buffer.c  | 5 +++--
 kernel/trace/trace.c        | 6 ++++--
 kernel/trace/trace_kdb.c    | 6 ++++--
 4 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index f1429675f252..1a40277b512c 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -128,7 +128,7 @@ ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
 		    unsigned long *lost_events);
 
 struct ring_buffer_iter *
-ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
+ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu, gfp_t flags);
 void ring_buffer_read_prepare_sync(void);
 void ring_buffer_read_start(struct ring_buffer_iter *iter);
 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9a91479bbbfe..41b6f96e5366 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4191,6 +4191,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_consume);
  * ring_buffer_read_prepare - Prepare for a non consuming read of the buffer
  * @buffer: The ring buffer to read from
  * @cpu: The cpu buffer to iterate over
+ * @flags: gfp flags to use for memory allocation
  *
  * This performs the initial preparations necessary to iterate
  * through the buffer.  Memory is allocated, buffer recording
@@ -4208,7 +4209,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_consume);
  * This overall must be paired with ring_buffer_read_finish.
  */
 struct ring_buffer_iter *
-ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu)
+ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu, gfp_t flags)
 {
 	struct ring_buffer_per_cpu *cpu_buffer;
 	struct ring_buffer_iter *iter;
@@ -4216,7 +4217,7 @@ ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu)
 	if (!cpumask_test_cpu(cpu, buffer->cpumask))
 		return NULL;
 
-	iter = kmalloc(sizeof(*iter), GFP_KERNEL);
+	iter = kmalloc(sizeof(*iter), flags);
 	if (!iter)
 		return NULL;
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e9cc47e59d25..ccd759eaad79 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4077,7 +4077,8 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
 	if (iter->cpu_file == RING_BUFFER_ALL_CPUS) {
 		for_each_tracing_cpu(cpu) {
 			iter->buffer_iter[cpu] =
-				ring_buffer_read_prepare(iter->trace_buffer->buffer, cpu);
+				ring_buffer_read_prepare(iter->trace_buffer->buffer,
+							 cpu, GFP_KERNEL);
 		}
 		ring_buffer_read_prepare_sync();
 		for_each_tracing_cpu(cpu) {
@@ -4087,7 +4088,8 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
 	} else {
 		cpu = iter->cpu_file;
 		iter->buffer_iter[cpu] =
-			ring_buffer_read_prepare(iter->trace_buffer->buffer, cpu);
+			ring_buffer_read_prepare(iter->trace_buffer->buffer,
+						 cpu, GFP_KERNEL);
 		ring_buffer_read_prepare_sync();
 		ring_buffer_read_start(iter->buffer_iter[cpu]);
 		tracing_iter_reset(iter, cpu);
diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
index d953c163a079..810d78a8d14c 100644
--- a/kernel/trace/trace_kdb.c
+++ b/kernel/trace/trace_kdb.c
@@ -51,14 +51,16 @@ static void ftrace_dump_buf(int skip_lines, long cpu_file)
 	if (cpu_file == RING_BUFFER_ALL_CPUS) {
 		for_each_tracing_cpu(cpu) {
 			iter.buffer_iter[cpu] =
-			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu);
+			ring_buffer_read_prepare(iter.trace_buffer->buffer,
+						 cpu, GFP_ATOMIC);
 			ring_buffer_read_start(iter.buffer_iter[cpu]);
 			tracing_iter_reset(&iter, cpu);
 		}
 	} else {
 		iter.cpu_file = cpu_file;
 		iter.buffer_iter[cpu_file] =
-			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu_file);
+			ring_buffer_read_prepare(iter.trace_buffer->buffer,
+						 cpu_file, GFP_ATOMIC);
 		ring_buffer_read_start(iter.buffer_iter[cpu_file]);
 		tracing_iter_reset(&iter, cpu_file);
 	}
-- 
2.20.1

[PATCH 4/8] tracing/probe: Check maxactive error cases

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Check maxactive on kprobe error case, because maxactive
is only for kretprobe, not for kprobe. Also, maxactive
should not be 0, it should be at least 1.

Link: http://lkml.kernel.org/r/155253780952.14922.15784129810238750331.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_kprobe.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ceafa0a2b1d1..a14837545295 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -624,7 +624,11 @@ static int trace_kprobe_create(int argc, const char *argv[])
 	if (event)
 		event++;
 
-	if (is_return && isdigit(argv[0][1])) {
+	if (isdigit(argv[0][1])) {
+		if (!is_return) {
+			pr_info("Maxactive is not for kprobe");
+			return -EINVAL;
+		}
 		if (event)
 			len = event - &argv[0][1] - 1;
 		else
@@ -634,8 +638,8 @@ static int trace_kprobe_create(int argc, const char *argv[])
 		memcpy(buf, &argv[0][1], len);
 		buf[len] = '\0';
 		ret = kstrtouint(buf, 0, &maxactive);
-		if (ret) {
-			pr_info("Failed to parse maxactive.\n");
+		if (ret || !maxactive) {
+			pr_info("Invalid maxactive number\n");
 			return ret;
 		}
 		/* kretprobes instances are iterated over via a list. The
-- 
2.20.1

[PATCH 5/8] tracing/probe: Check event name length correctly

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Ensure given name of event is not too long when parsing it,
and fix to update event name offset correctly when the group
name is given. For example, this makes probe event to check
the "p:foo/" error case correctly.

Link: http://lkml.kernel.org/r/155253782046.14922.14724124823730168629.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index cfcf77e6fb19..0dc13bff2847 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -159,6 +159,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 				char *buf)
 {
 	const char *slash, *event = *pevent;
+	int len;
 
 	slash = strchr(event, '/');
 	if (slash) {
@@ -173,10 +174,15 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 		strlcpy(buf, event, slash - event + 1);
 		*pgroup = buf;
 		*pevent = slash + 1;
+		event = *pevent;
 	}
-	if (strlen(event) == 0) {
+	len = strlen(event);
+	if (len == 0) {
 		pr_info("Event name is not specified\n");
 		return -EINVAL;
+	} else if (len > MAX_EVENT_NAME_LEN) {
+		pr_info("Event name is too long\n");
+		return -E2BIG;
 	}
 	return 0;
 }
-- 
2.20.1

[PATCH 6/8] tracing/probe: Check the size of argument name and body

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Check the size of argument name and expression is not 0
and smaller than maximum length.

Link: http://lkml.kernel.org/r/155253783029.14922.12650939303827581096.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.c | 2 ++
 kernel/trace/trace_probe.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 0dc13bff2847..bf9d3d7e0c9d 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -554,6 +554,8 @@ int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, char *arg,
 
 	body = strchr(arg, '=');
 	if (body) {
+		if (body - arg > MAX_ARG_NAME_LEN || body == arg)
+			return -EINVAL;
 		parg->name = kmemdup_nul(arg, body - arg, GFP_KERNEL);
 		body++;
 	} else {
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 8a63f8bc01bc..2177c206de15 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -32,6 +32,7 @@
 #define MAX_TRACE_ARGS		128
 #define MAX_ARGSTR_LEN		63
 #define MAX_ARRAY_LEN		64
+#define MAX_ARG_NAME_LEN	32
 #define MAX_STRING_SIZE		PATH_MAX
 
 /* Reserved field names */
-- 
2.20.1

[PATCH 7/8] tracing/probe: Check event/group naming rule at parsing

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Check event and group naming rule at parsing it instead
of allocating probes.

Link: http://lkml.kernel.org/r/155253784064.14922.2336893061156236237.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_kprobe.c | 7 +------
 kernel/trace/trace_probe.c  | 8 ++++++++
 kernel/trace/trace_uprobe.c | 5 +----
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index a14837545295..5265117ad7e8 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -221,7 +221,7 @@ static struct trace_kprobe *alloc_trace_kprobe(const char *group,
 
 	tk->rp.maxactive = maxactive;
 
-	if (!event || !is_good_name(event)) {
+	if (!event || !group) {
 		ret = -EINVAL;
 		goto error;
 	}
@@ -231,11 +231,6 @@ static struct trace_kprobe *alloc_trace_kprobe(const char *group,
 	if (!tk->tp.call.name)
 		goto error;
 
-	if (!group || !is_good_name(group)) {
-		ret = -EINVAL;
-		goto error;
-	}
-
 	tk->tp.class.system = kstrdup(group, GFP_KERNEL);
 	if (!tk->tp.class.system)
 		goto error;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index bf9d3d7e0c9d..8f8411e7835f 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -172,6 +172,10 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 			return -E2BIG;
 		}
 		strlcpy(buf, event, slash - event + 1);
+		if (!is_good_name(buf)) {
+			pr_info("Group name must follow the same rules as C identifiers\n");
+			return -EINVAL;
+		}
 		*pgroup = buf;
 		*pevent = slash + 1;
 		event = *pevent;
@@ -184,6 +188,10 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 		pr_info("Event name is too long\n");
 		return -E2BIG;
 	}
+	if (!is_good_name(event)) {
+		pr_info("Event name must follow the same rules as C identifiers\n");
+		return -EINVAL;
+	}
 	return 0;
 }
 
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index e335576b9411..52f033489377 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -266,10 +266,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
 {
 	struct trace_uprobe *tu;
 
-	if (!event || !is_good_name(event))
-		return ERR_PTR(-EINVAL);
-
-	if (!group || !is_good_name(group))
+	if (!event || !group)
 		return ERR_PTR(-EINVAL);
 
 	tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
-- 
2.20.1

[PATCH 8/8] tracing/probe: Verify alloc_trace_*probe() result

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Since alloc_trace_*probe() returns -EINVAL only if !event && !group,
it should not happen in trace_*probe_create(). If we catch that case
there is a bug. So use WARN_ON_ONCE() instead of pr_info().

Link: http://lkml.kernel.org/r/155253785078.14922.16902223633734601469.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_kprobe.c | 4 ++--
 kernel/trace/trace_uprobe.c | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 5265117ad7e8..63aa0ab56051 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -693,9 +693,9 @@ static int trace_kprobe_create(int argc, const char *argv[])
 	tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
 			       argc, is_return);
 	if (IS_ERR(tk)) {
-		pr_info("Failed to allocate trace_probe.(%d)\n",
-			(int)PTR_ERR(tk));
 		ret = PTR_ERR(tk);
+		/* This must return -ENOMEM otherwise there is a bug */
+		WARN_ON_ONCE(ret != -ENOMEM);
 		goto out;
 	}
 
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 52f033489377..b54137ec7810 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -514,8 +514,9 @@ static int trace_uprobe_create(int argc, const char **argv)
 
 	tu = alloc_trace_uprobe(group, event, argc, is_return);
 	if (IS_ERR(tu)) {
-		pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
 		ret = PTR_ERR(tu);
+		/* This must return -ENOMEM otherwise there is a bug */
+		WARN_ON_ONCE(ret != -ENOMEM);
 		goto fail_address_parse;
 	}
 	tu->offset = offset;
-- 
2.20.1