From b528c7ffdc3e56e6146d90bce3fcfd7db145fb89 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 28 Apr 2026 12:23:02 -0400 Subject: [PATCH] tracing/probes: Limit size of event probe to 3K commit b2aa3b4d64e460ac606f386c24e7d8a873ce6f1a upstream. 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 Acked-by: Masami Hiramatsu (Google) Fixes: 93ccae7a22274 ("tracing/kprobes: Support basic types on dynamic events") Link: https://patch.msgid.link/20260428122302.706610ba@gandalf.local.home Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_probe.c | 6 ++++++ kernel/trace/trace_probe.h | 4 +++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index d7adbf1536c8..d94d374b9d80 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -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); diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 08b5bda24da2..6149c4850382 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -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