fix(scap): set a null terminator when we collect args from /proc

Signed-off-by: Andrea Terzolo <[email protected]>

userspace/libscap/linux/scap_procs.c

@@ -658,26 +658,35 @@ static int32_t scap_proc_add_from_proc(struct scap_linux_platform* linux_platfor
 	{
 		ASSERT(sizeof(line) >= SCAP_MAX_ARGS_SIZE);
 
-		filesize = fread(line, 1, SCAP_MAX_ARGS_SIZE - 1, f);
+		filesize = fread(line, 1, SCAP_MAX_ARGS_SIZE, f);
 		if(filesize > 0)
 		{
-			line[filesize] = 0;
+			// In case `args` is greater than `SCAP_MAX_ARGS_SIZE` it could be
+			// truncated so we put a `/0` at the end manually.
+			line[filesize-1] = 0;
 
-			exe_len = strlen(line);
-			if(exe_len < filesize)
-			{
-				++exe_len;
-			}
+			// We always count also the terminator so `+1`
+			// Please note that this could be exactly `SCAP_MAX_ARGS_SIZE`
+			exe_len = strlen(line) + 1;
 
 			snprintf(tinfo.exe, SCAP_MAX_PATH_SIZE, "%s", line);
 
+			// Please note if `exe_len` is `SCAP_MAX_ARGS_SIZE` we will return an empty `args`.
 			tinfo.args_len = filesize - exe_len;
-
-			memcpy(tinfo.args, line + exe_len, tinfo.args_len);
-			tinfo.args[SCAP_MAX_ARGS_SIZE - 1] = 0;
+			if(tinfo.args_len > 0)
+			{
+				memcpy(tinfo.args, line + exe_len, tinfo.args_len);
+				tinfo.args[tinfo.args_len - 1] = 0;
+			}
+			else
+			{
+				tinfo.args_len = 0;
+				tinfo.args[0] = 0;
+			}
 		}
 		else
 		{
+			tinfo.args_len = 0;
 			tinfo.args[0] = 0;
 			tinfo.exe[0] = 0;
 		}
@@ -713,6 +722,7 @@ static int32_t scap_proc_add_from_proc(struct scap_linux_platform* linux_platfor
 		else
 		{
 			tinfo.env[0] = 0;
+			tinfo.env_len = 0;
 		}
 
 		fclose(f);

userspace/libsinsp/test/sinsp_utils.ut.cpp

@@ -208,3 +208,15 @@ TEST(sinsp_utils_test, sinsp_split_buf)
 	EXPECT_EQ(split[0], "hello");
 	EXPECT_EQ(split[1], "world");
 }
+
+TEST(sinsp_utils_test, sinsp_split_check_terminator)
+{
+	// check that the null terminator is enforced
+	const char *in = "hello\0worlddd";
+	size_t len = 13;
+	auto split = sinsp_split(in, len, '\0');
+
+	EXPECT_EQ(split.size(), 2);
+	EXPECT_EQ(split[0], "hello");
+	EXPECT_EQ(split[1], "worldd");
+}

userspace/libsinsp/utils.cpp

@@ -1392,14 +1392,21 @@ std::vector<std::string> sinsp_split(const char *buf, size_t len, char delim)
 		return {};
 	}
 
+	std::string s {buf, len - 1};
+
 	if(buf[len - 1] != '\0')
 	{
+#ifdef _DEBUG
 		throw sinsp_exception("expected a NUL-terminated buffer of size " +	
 							  std::to_string(len) + ", which instead ends with " +
 							  std::to_string(buf[len - 1]));
+#else
+		libsinsp_logger()->format(sinsp_logger::SEV_WARNING, "expected a NUL-terminated buffer of size '%ld' which instead ends with '%c'", len, buf[len - 1]);
+		// enforce the null terminator
+		s.replace(len-1, 1, "\0");
+#endif
 	}
 
-	std::string s {buf, len - 1};
 	return sinsp_split(s, delim);
 }