From: Pengpeng Hou <pengpeng@iscas.ac.cn>
Date: Wed, 1 Apr 2026 16:03:15 +0000 (+0800)
Subject: tracing/probe: reject non-closed empty immediate strings
X-Git-Tag: v7.0~12^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4346be6577aaa04586167402ae87bbdbe32484a4;p=thirdparty%2Fkernel%2Flinux.git

tracing/probe: reject non-closed empty immediate strings

parse_probe_arg() accepts quoted immediate strings and passes the body
after the opening quote to __parse_imm_string(). That helper currently
computes strlen(str) and immediately dereferences str[len - 1], which
underflows when the body is empty and not closed with double-quotation.

Reject empty non-closed immediate strings before checking for the closing quote.

Link: https://lore.kernel.org/all/20260401160315.88518-1-pengpeng@iscas.ac.cn/

Fixes: a42e3c4de964 ("tracing/probe: Add immediate string parameter support")
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index e0a5dc86c07e..e1c73065dae5 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -1068,7 +1068,7 @@ static int __parse_imm_string(char *str, char **pbuf, int offs)
 {
 	size_t len = strlen(str);
 
-	if (str[len - 1] != '"') {
+	if (!len || str[len - 1] != '"') {
 		trace_probe_log_err(offs + len, IMMSTR_NO_CLOSE);
 		return -EINVAL;
 	}