| /* |
| * KSM - NULL pointer dereference in ksm_do_scan() (CVE-2011-2183) |
| * |
| * This is a testcase from upstream commit: |
| * 2b472611a32a72f4a118c069c2d62a1a3f087afd. |
| * |
| * an exiting task can race against ksmd::scan_get_next_rmap_item |
| * (http://lkml.org/lkml/2011/6/1/742) easily triggering a NULL pointer |
| * dereference in ksmd. |
| * ksm_scan.mm_slot == &ksm_mm_head with only one registered mm |
| * |
| * CPU 1 (__ksm_exit) CPU 2 (scan_get_next_rmap_item) |
| * list_empty() is false |
| * lock slot == &ksm_mm_head |
| * list_del(slot->mm_list) |
| * (list now empty) |
| * unlock |
| * lock |
| * slot = list_entry(slot->mm_list.next) |
| * (list is empty, so slot is still ksm_mm_head) |
| * unlock |
| * slot->mm == NULL ... Oops |
| * |
| * Close this race by revalidating that the new slot is not simply the list |
| * head again. |
| * |
| * Test Prerequisites: |
| * |
| * *) ksm and ksmtuned daemons need to be disabled. Otherwise, it could |
| * distrub the testing as they also change some ksm tunables depends |
| * on current workloads. |
| * |
| * Copyright (C) 2011 Red Hat, Inc. |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of version 2 of the GNU General Public |
| * License as published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope that it would be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
| * |
| * Further, this software is distributed without any warranty that it |
| * is free of the rightful claim of any third person regarding |
| * infringement or the like. Any license provided herein, whether |
| * implied or otherwise, applies only to this software file. Patent |
| * licenses, if any, provided herein do not apply to combinations of |
| * this program with other software, or any other product whatsoever. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| * 02110-1301, USA. |
| */ |
| |
| #include <sys/types.h> |
| #include <sys/mman.h> |
| #include <sys/stat.h> |
| #include <sys/wait.h> |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <signal.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include "test.h" |
| #include "mem.h" |
| |
| char *TCID = "ksm05"; |
| int TST_TOTAL = 1; |
| |
| #ifdef HAVE_MADV_MERGEABLE |
| |
| static int ksm_run_orig; |
| |
| static void sighandler(int sig); |
| static void write_ksm_run(int val); |
| |
| int main(int argc, char *argv[]) |
| { |
| int lc, status; |
| long ps; |
| const char *msg; |
| pid_t pid; |
| void *ptr; |
| |
| msg = parse_opts(argc, argv, NULL, NULL); |
| if (msg != NULL) |
| tst_brkm(TBROK, tst_exit, "OPTION PARSING ERROR - %s", msg); |
| |
| ps = sysconf(_SC_PAGESIZE); |
| setup(); |
| |
| for (lc = 0; TEST_LOOPING(lc); lc++) { |
| tst_count = 0; |
| |
| switch (pid = fork()) { |
| case -1: |
| tst_brkm(TBROK | TERRNO, cleanup, "fork"); |
| case 0: |
| if (posix_memalign(&ptr, ps, ps) < 0) |
| tst_brkm(TBROK | TERRNO, cleanup, |
| "posix_memalign"); |
| if (madvise(ptr, ps, MADV_MERGEABLE) < 0) |
| tst_brkm(TBROK | TERRNO, cleanup, "madvise"); |
| *(char *)NULL = 0; /* SIGSEGV occurs as expected. */ |
| exit(0); |
| default: |
| break; |
| } |
| if (waitpid(pid, &status, WUNTRACED | WCONTINUED) == -1) |
| tst_brkm(TBROK | TERRNO, cleanup, "waitpid"); |
| if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) |
| tst_brkm(TBROK, cleanup, |
| "invalid signal received: %d", status); |
| } |
| |
| tst_resm(TPASS, "still alive."); |
| cleanup(); |
| tst_exit(); |
| } |
| |
| static void sighandler(int sig) |
| { |
| _exit((sig == SIGSEGV) ? 0 : sig); |
| } |
| |
| static void write_ksm_run(int val) |
| { |
| int fd; |
| char buf[BUFSIZ]; |
| |
| sprintf(buf, "%d", val); |
| fd = open(PATH_KSM "run", O_WRONLY); |
| if (fd == -1) |
| tst_brkm(TBROK | TERRNO, cleanup, "open"); |
| if (write(fd, buf, 1) != 1) |
| tst_brkm(TBROK | TERRNO, cleanup, "write"); |
| close(fd); |
| } |
| |
| void setup(void) |
| { |
| int fd; |
| char buf[BUFSIZ]; |
| |
| tst_require_root(NULL); |
| |
| if (tst_kvercmp(2, 6, 32) < 0) |
| tst_brkm(TCONF, NULL, "2.6.32 or greater kernel required."); |
| |
| if (access(PATH_KSM, F_OK) == -1) |
| tst_brkm(TCONF, NULL, "KSM configuration is not enabled"); |
| |
| tst_sig(FORK, sighandler, cleanup); |
| |
| TEST_PAUSE; |
| |
| /* save original /sys/kernel/mm/ksm/run value */ |
| fd = open(PATH_KSM "run", O_RDONLY); |
| if (fd == -1) |
| tst_brkm(TBROK | TERRNO, cleanup, "open"); |
| if (read(fd, buf, 1) != 1) |
| tst_brkm(TBROK | TERRNO, cleanup, "read"); |
| close(fd); |
| ksm_run_orig = atoi(buf); |
| |
| /* echo 1 > /sys/kernel/mm/ksm/run */ |
| if (ksm_run_orig != 1) |
| write_ksm_run(1); |
| } |
| |
| void cleanup(void) |
| { |
| /* restore /sys/kernel/mm/ksm/run value */ |
| if (ksm_run_orig != 1) |
| write_ksm_run(ksm_run_orig); |
| } |
| #else |
| int main(void) |
| { |
| tst_brkm(TCONF, NULL, "no MADV_MERGEABLE found."); |
| } |
| #endif |