| /** |
| * Copyright (C) 2020 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| #include <stdlib.h> |
| #include "../includes/common.h" |
| |
| //This PoC is only for 32-bit builds |
| #if _32_BIT |
| #include <unistd.h> |
| #include <string.h> |
| #include <dlfcn.h> |
| |
| #define MAX_STRLEN 256 |
| #define LOOP_COUNT 10 |
| #define LIB_NAME "/system/lib/libandroid.so" |
| |
| int runDlopenDlcloseLibraryLoop(char *libName, unsigned char count) { |
| while (count) { |
| void *lib_handle = dlopen(libName, RTLD_NOW); |
| if (!lib_handle) { |
| return EXIT_FAILURE; |
| } |
| if (dlclose(lib_handle)) { |
| return EXIT_FAILURE; |
| } |
| count--; |
| } |
| return EXIT_SUCCESS; |
| } |
| int getMemoryUsage(unsigned long *memUsage) { |
| char cmd[MAX_STRLEN]; |
| char buf[MAX_STRLEN]; |
| memset(cmd, 0, MAX_STRLEN); |
| memset(buf, 0, MAX_STRLEN); |
| sprintf(cmd, "cat /proc/%d/maps | grep anon:linker_alloc]", getpid()); |
| FILE *fpMem = popen(cmd, "r"); |
| if (!fpMem) { |
| return EXIT_FAILURE; |
| } |
| unsigned long totalMemUsage = 0; |
| while (fgets(buf, MAX_STRLEN, fpMem) != NULL) { |
| unsigned long mem1 = 0; |
| unsigned long mem2 = 0; |
| int numOfItemsRead = sscanf(buf, "%lx-%lx", &mem1, &mem2); |
| if (numOfItemsRead < 2) { |
| pclose(fpMem); |
| return EXIT_FAILURE; |
| } |
| totalMemUsage += mem2 - mem1; |
| } |
| pclose(fpMem); |
| *memUsage = totalMemUsage; |
| return EXIT_SUCCESS; |
| } |
| #endif /* _32_BIT */ |
| |
| int main() { |
| |
| //This PoC is only for 32-bit builds |
| #if _32_BIT |
| /* Memory usage is expected to rise during first few dlopen-dlcose pairs */ |
| /* due to linker initializations. Hence memory is not tracked during */ |
| /* first few dlopen-dlcose pairs. */ |
| if (runDlopenDlcloseLibraryLoop(LIB_NAME, LOOP_COUNT)) { |
| return EXIT_FAILURE; |
| } |
| |
| /* The linker specific initializations should be complete. Hence Memory */ |
| /* usage is tracked from this point onwards. Further dlopen-dlcose pairs */ |
| /* are not expected to increase memory usage */ |
| unsigned long memUsageBefore = 0; |
| if (getMemoryUsage(&memUsageBefore)) { |
| return EXIT_FAILURE; |
| } |
| |
| if (runDlopenDlcloseLibraryLoop(LIB_NAME, LOOP_COUNT)) { |
| return EXIT_FAILURE; |
| } |
| |
| unsigned long memUsageAfter = 0; |
| if (getMemoryUsage(&memUsageAfter)) { |
| return EXIT_FAILURE; |
| } |
| |
| if (memUsageBefore != memUsageAfter) { |
| return EXIT_VULNERABLE; |
| } |
| #endif /* _32_BIT */ |
| |
| return EXIT_SUCCESS; |
| } |