kernel/trace/kprobe_event_gen_test.c | 33 ++- kernel/trace/kprobe_event_gen_test.c.orig | 276 ++++++++++++++++++++++ 2 files changed, 301 insertions(+), 8 deletions(-) create mode 100644 kernel/trace/kprobe_event_gen_test.c.orig
From: Fidal palamparambil <rootuserhere@gmail.com>
This commit addresses several issues in the kprobe event generation test module:
1. Fixed NULL pointer management in error paths where trace_event_file pointers
were not properly set to NULL after errors, potentially causing double-free
or use-after-free issues.
2. Added comprehensive cleanup for the kprobe event when kretprobe initialization
fails in kprobe_event_gen_test_init(). Previously, a failed kretprobe creation
would leave the kprobe event dangling.
3. Enhanced error handling consistency between kprobe and kretprobe test functions,
ensuring both follow the same pattern for resource cleanup.
4. Fixed the error handling flow in test_gen_kprobe_cmd() and test_gen_kretprobe_cmd()
to properly set trace_event_file pointers to NULL when errors occur after
event creation but before successful completion.
The changes ensure proper resource management and prevent potential memory
corruption or leaks during module initialization and cleanup.
Signed-off-by: Fidal palamparambil <rootuserhere@gmail.com>
---
kernel/trace/kprobe_event_gen_test.c | 33 ++-
kernel/trace/kprobe_event_gen_test.c.orig | 276 ++++++++++++++++++++++
2 files changed, 301 insertions(+), 8 deletions(-)
create mode 100644 kernel/trace/kprobe_event_gen_test.c.orig
diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
index 5a4b722b5045..c9ab1c9bbf52 100644
--- a/kernel/trace/kprobe_event_gen_test.c
+++ b/kernel/trace/kprobe_event_gen_test.c
@@ -129,6 +129,7 @@ static int __init test_gen_kprobe_cmd(void)
"gen_kprobe_test");
if (IS_ERR(gen_kprobe_test)) {
ret = PTR_ERR(gen_kprobe_test);
+ gen_kprobe_test = NULL;
goto delete;
}
@@ -137,14 +138,13 @@ static int __init test_gen_kprobe_cmd(void)
"kprobes", "gen_kprobe_test", true);
if (ret) {
trace_put_event_file(gen_kprobe_test);
+ gen_kprobe_test = NULL;
goto delete;
}
out:
kfree(buf);
return ret;
delete:
- if (trace_event_file_is_valid(gen_kprobe_test))
- gen_kprobe_test = NULL;
/* We got an error after creating the event, delete it */
kprobe_event_delete("gen_kprobe_test");
goto out;
@@ -194,6 +194,7 @@ static int __init test_gen_kretprobe_cmd(void)
"gen_kretprobe_test");
if (IS_ERR(gen_kretprobe_test)) {
ret = PTR_ERR(gen_kretprobe_test);
+ gen_kretprobe_test = NULL;
goto delete;
}
@@ -202,14 +203,13 @@ static int __init test_gen_kretprobe_cmd(void)
"kprobes", "gen_kretprobe_test", true);
if (ret) {
trace_put_event_file(gen_kretprobe_test);
+ gen_kretprobe_test = NULL;
goto delete;
}
out:
kfree(buf);
return ret;
delete:
- if (trace_event_file_is_valid(gen_kretprobe_test))
- gen_kretprobe_test = NULL;
/* We got an error after creating the event, delete it */
kprobe_event_delete("gen_kretprobe_test");
goto out;
@@ -220,11 +220,21 @@ static int __init kprobe_event_gen_test_init(void)
int ret;
ret = test_gen_kprobe_cmd();
- if (ret)
+ if (ret) {
+ /* Clean up kprobe event if it was partially created */
+ if (trace_event_file_is_valid(gen_kprobe_test)) {
+ WARN_ON(trace_array_set_clr_event(gen_kprobe_test->tr,
+ "kprobes",
+ "gen_kprobe_test", false));
+ trace_put_event_file(gen_kprobe_test);
+ }
+ WARN_ON(kprobe_event_delete("gen_kprobe_test"));
return ret;
+ }
ret = test_gen_kretprobe_cmd();
if (ret) {
+ /* Clean up kretprobe event if it was partially created */
if (trace_event_file_is_valid(gen_kretprobe_test)) {
WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,
"kprobes",
@@ -232,6 +242,15 @@ static int __init kprobe_event_gen_test_init(void)
trace_put_event_file(gen_kretprobe_test);
}
WARN_ON(kprobe_event_delete("gen_kretprobe_test"));
+
+ /* Also clean up the successfully created kprobe event */
+ if (trace_event_file_is_valid(gen_kprobe_test)) {
+ WARN_ON(trace_array_set_clr_event(gen_kprobe_test->tr,
+ "kprobes",
+ "gen_kprobe_test", false));
+ trace_put_event_file(gen_kprobe_test);
+ }
+ WARN_ON(kprobe_event_delete("gen_kprobe_test"));
}
return ret;
@@ -249,7 +268,6 @@ static void __exit kprobe_event_gen_test_exit(void)
trace_put_event_file(gen_kprobe_test);
}
-
/* Now unregister and free the event */
WARN_ON(kprobe_event_delete("gen_kprobe_test"));
@@ -263,7 +281,6 @@ static void __exit kprobe_event_gen_test_exit(void)
trace_put_event_file(gen_kretprobe_test);
}
-
/* Now unregister and free the event */
WARN_ON(kprobe_event_delete("gen_kretprobe_test"));
}
@@ -273,4 +290,4 @@ module_exit(kprobe_event_gen_test_exit)
MODULE_AUTHOR("Tom Zanussi");
MODULE_DESCRIPTION("kprobe event generation test");
-MODULE_LICENSE("GPL v2");
+MODULE_LICENSE("GPL v2");
\ No newline at end of file
diff --git a/kernel/trace/kprobe_event_gen_test.c.orig b/kernel/trace/kprobe_event_gen_test.c.orig
new file mode 100644
index 000000000000..5a4b722b5045
--- /dev/null
+++ b/kernel/trace/kprobe_event_gen_test.c.orig
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test module for in-kernel kprobe event creation and generation.
+ *
+ * Copyright (C) 2019 Tom Zanussi <zanussi@kernel.org>
+ */
+
+#include <linux/module.h>
+#include <linux/trace_events.h>
+
+/*
+ * This module is a simple test of basic functionality for in-kernel
+ * kprobe/kretprobe event creation. The first test uses
+ * kprobe_event_gen_cmd_start(), kprobe_event_add_fields() and
+ * kprobe_event_gen_cmd_end() to create a kprobe event, which is then
+ * enabled in order to generate trace output. The second creates a
+ * kretprobe event using kretprobe_event_gen_cmd_start() and
+ * kretprobe_event_gen_cmd_end(), and is also then enabled.
+ *
+ * To test, select CONFIG_KPROBE_EVENT_GEN_TEST and build the module.
+ * Then:
+ *
+ * # insmod kernel/trace/kprobe_event_gen_test.ko
+ * # cat /sys/kernel/tracing/trace
+ *
+ * You should see many instances of the "gen_kprobe_test" and
+ * "gen_kretprobe_test" events in the trace buffer.
+ *
+ * To remove the events, remove the module:
+ *
+ * # rmmod kprobe_event_gen_test
+ *
+ */
+
+static struct trace_event_file *gen_kprobe_test;
+static struct trace_event_file *gen_kretprobe_test;
+
+#define KPROBE_GEN_TEST_FUNC "do_sys_open"
+
+/* X86 */
+#if defined(CONFIG_X86_64) || defined(CONFIG_X86_32)
+#define KPROBE_GEN_TEST_ARG0 "dfd=%ax"
+#define KPROBE_GEN_TEST_ARG1 "filename=%dx"
+#define KPROBE_GEN_TEST_ARG2 "flags=%cx"
+#define KPROBE_GEN_TEST_ARG3 "mode=+4($stack)"
+
+/* ARM64 */
+#elif defined(CONFIG_ARM64)
+#define KPROBE_GEN_TEST_ARG0 "dfd=%x0"
+#define KPROBE_GEN_TEST_ARG1 "filename=%x1"
+#define KPROBE_GEN_TEST_ARG2 "flags=%x2"
+#define KPROBE_GEN_TEST_ARG3 "mode=%x3"
+
+/* ARM */
+#elif defined(CONFIG_ARM)
+#define KPROBE_GEN_TEST_ARG0 "dfd=%r0"
+#define KPROBE_GEN_TEST_ARG1 "filename=%r1"
+#define KPROBE_GEN_TEST_ARG2 "flags=%r2"
+#define KPROBE_GEN_TEST_ARG3 "mode=%r3"
+
+/* RISCV */
+#elif defined(CONFIG_RISCV)
+#define KPROBE_GEN_TEST_ARG0 "dfd=%a0"
+#define KPROBE_GEN_TEST_ARG1 "filename=%a1"
+#define KPROBE_GEN_TEST_ARG2 "flags=%a2"
+#define KPROBE_GEN_TEST_ARG3 "mode=%a3"
+
+/* others */
+#else
+#define KPROBE_GEN_TEST_ARG0 NULL
+#define KPROBE_GEN_TEST_ARG1 NULL
+#define KPROBE_GEN_TEST_ARG2 NULL
+#define KPROBE_GEN_TEST_ARG3 NULL
+#endif
+
+static bool trace_event_file_is_valid(struct trace_event_file *input)
+{
+ return input && !IS_ERR(input);
+}
+
+/*
+ * Test to make sure we can create a kprobe event, then add more
+ * fields.
+ */
+static int __init test_gen_kprobe_cmd(void)
+{
+ struct dynevent_cmd cmd;
+ char *buf;
+ int ret;
+
+ /* Create a buffer to hold the generated command */
+ buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ /* Before generating the command, initialize the cmd object */
+ kprobe_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);
+
+ /*
+ * Define the gen_kprobe_test event with the first 2 kprobe
+ * fields.
+ */
+ ret = kprobe_event_gen_cmd_start(&cmd, "gen_kprobe_test",
+ KPROBE_GEN_TEST_FUNC,
+ KPROBE_GEN_TEST_ARG0, KPROBE_GEN_TEST_ARG1);
+ if (ret)
+ goto out;
+
+ /* Use kprobe_event_add_fields to add the rest of the fields */
+
+ ret = kprobe_event_add_fields(&cmd, KPROBE_GEN_TEST_ARG2, KPROBE_GEN_TEST_ARG3);
+ if (ret)
+ goto out;
+
+ /*
+ * This actually creates the event.
+ */
+ ret = kprobe_event_gen_cmd_end(&cmd);
+ if (ret)
+ goto out;
+
+ /*
+ * Now get the gen_kprobe_test event file. We need to prevent
+ * the instance and event from disappearing from underneath
+ * us, which trace_get_event_file() does (though in this case
+ * we're using the top-level instance which never goes away).
+ */
+ gen_kprobe_test = trace_get_event_file(NULL, "kprobes",
+ "gen_kprobe_test");
+ if (IS_ERR(gen_kprobe_test)) {
+ ret = PTR_ERR(gen_kprobe_test);
+ goto delete;
+ }
+
+ /* Enable the event or you won't see anything */
+ ret = trace_array_set_clr_event(gen_kprobe_test->tr,
+ "kprobes", "gen_kprobe_test", true);
+ if (ret) {
+ trace_put_event_file(gen_kprobe_test);
+ goto delete;
+ }
+ out:
+ kfree(buf);
+ return ret;
+ delete:
+ if (trace_event_file_is_valid(gen_kprobe_test))
+ gen_kprobe_test = NULL;
+ /* We got an error after creating the event, delete it */
+ kprobe_event_delete("gen_kprobe_test");
+ goto out;
+}
+
+/*
+ * Test to make sure we can create a kretprobe event.
+ */
+static int __init test_gen_kretprobe_cmd(void)
+{
+ struct dynevent_cmd cmd;
+ char *buf;
+ int ret;
+
+ /* Create a buffer to hold the generated command */
+ buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ /* Before generating the command, initialize the cmd object */
+ kprobe_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);
+
+ /*
+ * Define the kretprobe event.
+ */
+ ret = kretprobe_event_gen_cmd_start(&cmd, "gen_kretprobe_test",
+ KPROBE_GEN_TEST_FUNC,
+ "$retval");
+ if (ret)
+ goto out;
+
+ /*
+ * This actually creates the event.
+ */
+ ret = kretprobe_event_gen_cmd_end(&cmd);
+ if (ret)
+ goto out;
+
+ /*
+ * Now get the gen_kretprobe_test event file. We need to
+ * prevent the instance and event from disappearing from
+ * underneath us, which trace_get_event_file() does (though in
+ * this case we're using the top-level instance which never
+ * goes away).
+ */
+ gen_kretprobe_test = trace_get_event_file(NULL, "kprobes",
+ "gen_kretprobe_test");
+ if (IS_ERR(gen_kretprobe_test)) {
+ ret = PTR_ERR(gen_kretprobe_test);
+ goto delete;
+ }
+
+ /* Enable the event or you won't see anything */
+ ret = trace_array_set_clr_event(gen_kretprobe_test->tr,
+ "kprobes", "gen_kretprobe_test", true);
+ if (ret) {
+ trace_put_event_file(gen_kretprobe_test);
+ goto delete;
+ }
+ out:
+ kfree(buf);
+ return ret;
+ delete:
+ if (trace_event_file_is_valid(gen_kretprobe_test))
+ gen_kretprobe_test = NULL;
+ /* We got an error after creating the event, delete it */
+ kprobe_event_delete("gen_kretprobe_test");
+ goto out;
+}
+
+static int __init kprobe_event_gen_test_init(void)
+{
+ int ret;
+
+ ret = test_gen_kprobe_cmd();
+ if (ret)
+ return ret;
+
+ ret = test_gen_kretprobe_cmd();
+ if (ret) {
+ if (trace_event_file_is_valid(gen_kretprobe_test)) {
+ WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,
+ "kprobes",
+ "gen_kretprobe_test", false));
+ trace_put_event_file(gen_kretprobe_test);
+ }
+ WARN_ON(kprobe_event_delete("gen_kretprobe_test"));
+ }
+
+ return ret;
+}
+
+static void __exit kprobe_event_gen_test_exit(void)
+{
+ if (trace_event_file_is_valid(gen_kprobe_test)) {
+ /* Disable the event or you can't remove it */
+ WARN_ON(trace_array_set_clr_event(gen_kprobe_test->tr,
+ "kprobes",
+ "gen_kprobe_test", false));
+
+ /* Now give the file and instance back */
+ trace_put_event_file(gen_kprobe_test);
+ }
+
+
+ /* Now unregister and free the event */
+ WARN_ON(kprobe_event_delete("gen_kprobe_test"));
+
+ if (trace_event_file_is_valid(gen_kretprobe_test)) {
+ /* Disable the event or you can't remove it */
+ WARN_ON(trace_array_set_clr_event(gen_kretprobe_test->tr,
+ "kprobes",
+ "gen_kretprobe_test", false));
+
+ /* Now give the file and instance back */
+ trace_put_event_file(gen_kretprobe_test);
+ }
+
+
+ /* Now unregister and free the event */
+ WARN_ON(kprobe_event_delete("gen_kretprobe_test"));
+}
+
+module_init(kprobe_event_gen_test_init)
+module_exit(kprobe_event_gen_test_exit)
+
+MODULE_AUTHOR("Tom Zanussi");
+MODULE_DESCRIPTION("kprobe event generation test");
+MODULE_LICENSE("GPL v2");
--
2.50.1.windows.1On Sat, Sep 06, 2025 at 05:15:59PM +0400, Fidal Palamparambil wrote: > From: Fidal palamparambil <rootuserhere@gmail.com> > > This commit addresses several issues in the kprobe event generation test module: > > 1. Fixed NULL pointer management in error paths where trace_event_file pointers > were not properly set to NULL after errors, potentially causing double-free > or use-after-free issues. > > 2. Added comprehensive cleanup for the kprobe event when kretprobe initialization > fails in kprobe_event_gen_test_init(). Previously, a failed kretprobe creation > would leave the kprobe event dangling. > > 3. Enhanced error handling consistency between kprobe and kretprobe test functions, > ensuring both follow the same pattern for resource cleanup. > > 4. Fixed the error handling flow in test_gen_kprobe_cmd() and test_gen_kretprobe_cmd() > to properly set trace_event_file pointers to NULL when errors occur after > event creation but before successful completion. > > The changes ensure proper resource management and prevent potential memory > corruption or leaks during module initialization and cleanup. > > Signed-off-by: Fidal palamparambil <rootuserhere@gmail.com> Please just stop. Luis
> This commit addresses several issues …
See also:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.17-rc4#n94
…
> +++ b/kernel/trace/kprobe_event_gen_test.c
> @@ -129,6 +129,7 @@ static int __init test_gen_kprobe_cmd(void)
> "gen_kprobe_test");
> if (IS_ERR(gen_kprobe_test)) {
> ret = PTR_ERR(gen_kprobe_test);
> + gen_kprobe_test = NULL;
May the repetition be reduced for this assignment statement?
> goto delete;
How do you think about to use an additional label?
> }
…
Regards,
Markus
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