Commit b2aa3b4d authored by Steven Rostedt's avatar Steven Rostedt
Browse files

tracing/probes: Limit size of event probe to 3K 



There currently isn't a max limit an event probe can be. One could make an
event greater than PAGE_SIZE, which makes the event useless because if
it's bigger than the max event that can be recorded into the ring buffer,
then it will never be recorded.

A event probe should never need to be greater than 3K, so make that the
max size. As long as the max is less than the max that can be recorded
onto the ring buffer, it should be fine.

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: 93ccae7a ("tracing/kprobes: Support basic types on dynamic events")
Link: https://patch.msgid.link/20260428122302.706610ba@gandalf.local.home


Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 5ec07d52

kernel/trace/trace_probe.c

+6 −0
Original line number Diff line number Diff line
@@ -1523,6 +1523,12 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, 
	parg->offset = *size;

	*size += parg->type->size * (parg->count ?: 1);



	if (*size > MAX_PROBE_EVENT_SIZE) {

		ret = -E2BIG;

		trace_probe_log_err(ctx->offset, EVENT_TOO_BIG);

		goto fail;

	}



	if (parg->count) {

		len = strlen(parg->type->fmttype) + 6;

		parg->fmt = kmalloc(len, GFP_KERNEL);

kernel/trace/trace_probe.h

+3 −1
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 
#define MAX_BTF_ARGS_LEN	128

#define MAX_DENTRY_ARGS_LEN	256

#define MAX_STRING_SIZE		PATH_MAX

#define MAX_PROBE_EVENT_SIZE	3072



/* Reserved field names */

#define FIELD_STRING_IP		"__probe_ip"
@@ -561,7 +562,8 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, 
	C(BAD_TYPE4STR,		"This type does not fit for string."),\

	C(NEED_STRING_TYPE,	"$comm and immediate-string only accepts string type"),\

	C(TOO_MANY_ARGS,	"Too many arguments are specified"),	\

	C(TOO_MANY_EARGS,	"Too many entry arguments specified"),

	C(TOO_MANY_EARGS,	"Too many entry arguments specified"),	\

	C(EVENT_TOO_BIG,	"Event too big (too many fields?)"),



#undef C

#define C(a, b)		TP_ERR_##a