[PATCH v2 1/6] tracing: probe: Allocate traceprobe_parse_context from heap

Masami Hiramatsu (Google)
2025-07-20T06:21:51Z

Instead of allocating traceprobe_parse_context on stack, allocate it
dynamically from heap (slab).

This change is likely intended to prevent potential stack overflow
issues, which can be a concern in the kernel environment where stack
space is limited.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506240416.nZIhDXoO-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Sort #include alphabetically.
- Just NULL check for freeing traceprobe_parse_context.
- Do not change the semantics of traceprobe_parse_context for uprobe
event. (alloc/free in loop)
---
kernel/trace/trace_eprobe.c | 14 ++++++++------
kernel/trace/trace_fprobe.c | 13 ++++++++-----
kernel/trace/trace_kprobe.c | 10 +++++++---
kernel/trace/trace_probe.h | 26 ++++++++++++++++++--------
kernel/trace/trace_uprobe.c | 13 ++++++++-----
5 files changed, 49 insertions(+), 27 deletions(-)

diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index 916555f0de81..1e18a8619b40 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -797,18 +797,20 @@ find_and_get_event(const char *system, const char *event_name)

static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[], int i)
{
- struct traceprobe_parse_context ctx = {
- .event = ep->event,
- .flags = TPARG_FL_KERNEL | TPARG_FL_TEVENT,
- };
+ struct traceprobe_parse_context *ctx __free(traceprobe_parse_context) = NULL;
int ret;

- ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], &ctx);
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+ ctx->event = ep->event;
+ ctx->flags = TPARG_FL_KERNEL | TPARG_FL_TEVENT;
+
+ ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], ctx);
/* Handle symbols "@" */
if (!ret)
ret = traceprobe_update_arg(&ep->tp.args[i]);

- traceprobe_finish_parse(&ctx);
return ret;
}

diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index dbf9d413125a..264cf7fc9a1d 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -1383,14 +1383,17 @@ static int trace_fprobe_create_internal(int argc, const char *argv[],

static int trace_fprobe_create_cb(int argc, const char *argv[])
{
- struct traceprobe_parse_context ctx = {
- .flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE,
- };
+ struct traceprobe_parse_context *ctx __free(traceprobe_parse_context) = NULL;
int ret;

+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE,
+
trace_probe_log_init("trace_fprobe", argc, argv);
- ret = trace_fprobe_create_internal(argc, argv, &ctx);
- traceprobe_finish_parse(&ctx);
+ ret = trace_fprobe_create_internal(argc, argv, ctx);
trace_probe_log_clear();
return ret;
}
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 3e5c47b6d7b2..15d7a381a128 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1065,14 +1065,18 @@ static int trace_kprobe_create_internal(int argc, const char *argv[],

static int trace_kprobe_create_cb(int argc, const char *argv[])
{
- struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL };
+ struct traceprobe_parse_context *ctx __free(traceprobe_parse_context) = NULL;
int ret;

+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+ ctx->flags = TPARG_FL_KERNEL;
+
trace_probe_log_init("trace_kprobe", argc, argv);

- ret = trace_kprobe_create_internal(argc, argv, &ctx);
+ ret = trace_kprobe_create_internal(argc, argv, ctx);

- traceprobe_finish_parse(&ctx);
trace_probe_log_clear();
return ret;
}
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 854e5668f5ee..842383fbc03b 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -10,20 +10,22 @@
* Author: Srikar Dronamraju
*/

+#include <linux/bitops.h>
+#include <linux/btf.h>
+#include <linux/cleanup.h>
+#include <linux/kprobes.h>
+#include <linux/limits.h>
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/smp.h>
-#include <linux/tracefs.h>
-#include <linux/types.h>
#include <linux/string.h>
-#include <linux/ptrace.h>
-#include <linux/perf_event.h>
-#include <linux/kprobes.h>
#include <linux/stringify.h>
-#include <linux/limits.h>
+#include <linux/tracefs.h>
+#include <linux/types.h>
#include <linux/uaccess.h>
-#include <linux/bitops.h>
-#include <linux/btf.h>
+
#include <asm/bitsperlong.h>

#include "trace.h"
@@ -438,6 +440,14 @@ extern void traceprobe_free_probe_arg(struct probe_arg *arg);
* this MUST be called for clean up the context and return a resource.
*/
void traceprobe_finish_parse(struct traceprobe_parse_context *ctx);
+static inline void traceprobe_free_parse_ctx(struct traceprobe_parse_context *ctx)
+{
+ traceprobe_finish_parse(ctx);
+ kfree(ctx);
+}
+
+DEFINE_FREE(traceprobe_parse_context, struct traceprobe_parse_context *,
+ if (_T) traceprobe_free_parse_ctx(_T))

extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index f95a2c3d5b1b..797ac1250956 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -695,13 +695,16 @@ static int __trace_uprobe_create(int argc, const char **argv)

/* parse arguments */
for (i = 0; i < argc; i++) {
- struct traceprobe_parse_context ctx = {
- .flags = (is_return ? TPARG_FL_RETURN : 0) | TPARG_FL_USER,
- };
+ struct traceprobe_parse_context *ctx __free(traceprobe_parse_context)
+ = kzalloc(sizeof(*ctx), GFP_KERNEL);

+ if (!ctx) {
+ ret = -ENOMEM;
+ goto error;
+ }
+ ctx->flags = (is_return ? TPARG_FL_RETURN : 0) | TPARG_FL_USER;
trace_probe_log_set_index(i + 2);
- ret = traceprobe_parse_probe_arg(&tu->tp, i, argv[i], &ctx);
- traceprobe_finish_parse(&ctx);
+ ret = traceprobe_parse_probe_arg(&tu->tp, i, argv[i], ctx);
if (ret)
goto error;
}