[PATCH] tracing/probes: Treating longer symbol name on event comparation
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2026-07-28 04:40:15
Also in:
lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Masami Hiramatsu (Google) <mhiramat@kernel.org> MAX_COMMON_HEAD_LEN (63) was used to allocate a temporary buffer for formatting command heads in trace_kprobe_match_command_head() and trace_uprobe_match_command_head(). However, the buffer size is too short for some longer symbols. Especially, with rust code, the symbol can be mangled and become very long. Refactor trace_kprobe_match_command_head() to perform direct string comparisons using strcmp() and strncmp(), eliminating the need for a temporary buffer and removing the MAX_COMMON_HEAD_LEN string length restriction on probe symbol names. For trace_uprobe_match_command_head(), since tu->filename is already matched via strncmp(), use a fixed 64-byte stack buffer solely for formatting offset and ref_ctr_offset (which requires at most 39 bytes). With all users converted, remove the MAX_COMMON_HEAD_LEN definition from trace_probe.h. Reported-by: Zhan Xusheng <redacted> Link: https://lore.kernel.org/all/20260724023317.624074-1-zhanxusheng@xiaomi.com/ (local) Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> --- base-commit: 5be3a9db600853578559681b2dd20a9bc7dd4fc5 --- kernel/trace/trace_kprobe.c | 24 ++++++++++++++++-------- kernel/trace/trace_probe.h | 1 - kernel/trace/trace_uprobe.c | 2 +- 3 files changed, 17 insertions(+), 10 deletions(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c25f902aa1a6..e41a7c113646 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c@@ -149,20 +149,28 @@ static bool trace_kprobe_is_busy(struct dyn_event *ev) static bool trace_kprobe_match_command_head(struct trace_kprobe *tk, int argc, const char **argv) { - char buf[MAX_COMMON_HEAD_LEN + 1]; + char buf[32]; + int len; if (!argc) return true; - if (!tk->symbol) + if (!tk->symbol) { snprintf(buf, sizeof(buf), "0x%p", tk->rp.kp.addr); - else if (tk->rp.kp.offset) - snprintf(buf, sizeof(buf), "%s+%u", - trace_kprobe_symbol(tk), tk->rp.kp.offset); - else - snprintf(buf, sizeof(buf), "%s", trace_kprobe_symbol(tk)); - if (strcmp(buf, argv[0])) + if (strcmp(buf, argv[0])) + return false; + } else if (tk->rp.kp.offset) { + len = strlen(trace_kprobe_symbol(tk)); + if (strncmp(trace_kprobe_symbol(tk), argv[0], len) || + argv[0][len] != '+') + return false; + + snprintf(buf, sizeof(buf), "%u", tk->rp.kp.offset); + if (strcmp(buf, &argv[0][len + 1])) + return false; + } else if (strcmp(trace_kprobe_symbol(tk), argv[0])) return false; + argc--; argv++; return trace_probe_match_command_args(&tk->tp, argc, argv);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index c0f05763811c..fba1af092a9b 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h@@ -33,7 +33,6 @@ #define MAX_TRACE_ARGS 128 #define MAX_ARGSTR_LEN 255 -#define MAX_COMMON_HEAD_LEN 63 #define MAX_ARRAY_LEN 64 #define MAX_ARG_NAME_LEN 32 #define MAX_BTF_ARGS_LEN 128
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 67bd8fd91e3e..861d857adadb 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c@@ -281,7 +281,7 @@ static bool trace_uprobe_is_busy(struct dyn_event *ev) static bool trace_uprobe_match_command_head(struct trace_uprobe *tu, int argc, const char **argv) { - char buf[MAX_COMMON_HEAD_LEN + 1]; + char buf[64]; int len; if (!argc)