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-rw-r--r--meta/recipes-core/glibc/glibc/0002-CVE-2021-3999.patch357
1 files changed, 357 insertions, 0 deletions
diff --git a/meta/recipes-core/glibc/glibc/0002-CVE-2021-3999.patch b/meta/recipes-core/glibc/glibc/0002-CVE-2021-3999.patch
new file mode 100644
index 00000000000..ef3a504fdfb
--- /dev/null
+++ b/meta/recipes-core/glibc/glibc/0002-CVE-2021-3999.patch
@@ -0,0 +1,357 @@
+From 472e799a5f2102bc0c3206dbd5a801765fceb39c Mon Sep 17 00:00:00 2001
+From: Siddhesh Poyarekar <siddhesh@sourceware.org>
+Date: Fri, 21 Jan 2022 23:32:56 +0530
+Subject: [PATCH] getcwd: Set errno to ERANGE for size == 1 (CVE-2021-3999)
+
+No valid path returned by getcwd would fit into 1 byte, so reject the
+size early and return NULL with errno set to ERANGE. This change is
+prompted by CVE-2021-3999, which describes a single byte buffer
+underflow and overflow when all of the following conditions are met:
+
+- The buffer size (i.e. the second argument of getcwd) is 1 byte
+- The current working directory is too long
+- '/' is also mounted on the current working directory
+
+Sequence of events:
+
+- In sysdeps/unix/sysv/linux/getcwd.c, the syscall returns ENAMETOOLONG
+ because the linux kernel checks for name length before it checks
+ buffer size
+
+- The code falls back to the generic getcwd in sysdeps/posix
+
+- In the generic func, the buf[0] is set to '\0' on line 250
+
+- this while loop on line 262 is bypassed:
+
+ while (!(thisdev == rootdev && thisino == rootino))
+
+ since the rootfs (/) is bind mounted onto the directory and the flow
+ goes on to line 449, where it puts a '/' in the byte before the
+ buffer.
+
+- Finally on line 458, it moves 2 bytes (the underflowed byte and the
+ '\0') to the buf[0] and buf[1], resulting in a 1 byte buffer overflow.
+
+- buf is returned on line 469 and errno is not set.
+
+This resolves BZ #28769.
+
+Reviewed-by: Andreas Schwab <schwab@linux-m68k.org>
+Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
+Signed-off-by: Qualys Security Advisory <qsa@qualys.com>
+Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
+(cherry picked from commit 23e0e8f5f1fb5ed150253d986ecccdc90c2dcd5e)
+
+Upstream-Status: Backport [https://sourceware.org/git/?p=glibc.git;a=commit;h=472e799a5f2102bc0c3206dbd5a801765fceb39c]
+CVE: CVE-2021-3999
+
+Signed-off-by: Pgowda <pgowda.cve@gmail.com>
+---
+ NEWS | 6 +
+ sysdeps/posix/getcwd.c | 7 +
+ sysdeps/unix/sysv/linux/Makefile | 7 +-
+ .../unix/sysv/linux/tst-getcwd-smallbuff.c | 241 ++++++++++++++++++
+ 4 files changed, 260 insertions(+), 1 deletion(-)
+ create mode 100644 sysdeps/unix/sysv/linux/tst-getcwd-smallbuff.c
+
+diff --git a/NEWS b/NEWS
+index b4f81c2668..8d7467d2c1 100644
+--- a/NEWS
++++ b/NEWS
+@@ -214,6 +214,12 @@ Security related changes:
+ function could result in a memory leak and potential access of
+ uninitialized memory. Reported by Qualys.
+
++ CVE-2021-3999: Passing a buffer of size exactly 1 byte to the getcwd
++ function may result in an off-by-one buffer underflow and overflow
++ when the current working directory is longer than PATH_MAX and also
++ corresponds to the / directory through an unprivileged mount
++ namespace. Reported by Qualys.
++
+ The following bugs are resolved with this release:
+
+ [4737] libc: fork is not async-signal-safe
+diff --git a/sysdeps/posix/getcwd.c b/sysdeps/posix/getcwd.c
+index 13680026ff..b6984a382c 100644
+--- a/sysdeps/posix/getcwd.c
++++ b/sysdeps/posix/getcwd.c
+@@ -187,6 +187,13 @@ __getcwd_generic (char *buf, size_t size
+ size_t allocated = size;
+ size_t used;
+
++ /* A size of 1 byte is never useful. */
++ if (allocated == 1)
++ {
++ __set_errno (ERANGE);
++ return NULL;
++ }
++
+ #if HAVE_MINIMALLY_WORKING_GETCWD
+ /* If AT_FDCWD is not defined, the algorithm below is O(N**2) and
+ this is much slower than the system getcwd (at least on
+diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
+index 76ad06361c..9380d3848d 100644
+--- a/sysdeps/unix/sysv/linux/Makefile
++++ b/sysdeps/unix/sysv/linux/Makefile
+@@ -331,7 +331,12 @@ sysdep_routines += xstatconv internal_st
+
+ sysdep_headers += bits/fcntl-linux.h
+
+-tests += tst-fallocate tst-fallocate64 tst-o_path-locks
++tests += \
++ tst-fallocate \
++ tst-fallocate64 \
++ tst-getcwd-smallbuff \
++ tst-o_path-locks \
++# tests
+ endif
+
+ ifeq ($(subdir),elf)
+diff --git a/sysdeps/unix/sysv/linux/tst-getcwd-smallbuff.c b/sysdeps/unix/sysv/linux/tst-getcwd-smallbuff.c
+new file mode 100644
+index 0000000000..d460d6e766
+--- /dev/null
++++ b/sysdeps/unix/sysv/linux/tst-getcwd-smallbuff.c
+@@ -0,0 +1,241 @@
++/* Verify that getcwd returns ERANGE for size 1 byte and does not underflow
++ buffer when the CWD is too long and is also a mount target of /. See bug
++ #28769 or CVE-2021-3999 for more context.
++ Copyright The GNU Toolchain Authors.
++ This file is part of the GNU C Library.
++
++ The GNU C Library is free software; you can redistribute it and/or
++ modify it under the terms of the GNU Lesser General Public
++ License as published by the Free Software Foundation; either
++ version 2.1 of the License, or (at your option) any later version.
++
++ The GNU C Library is distributed in the hope that it will be useful,
++ but WITHOUT ANY WARRANTY; without even the implied warranty of
++ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
++ Lesser General Public License for more details.
++
++ You should have received a copy of the GNU Lesser General Public
++ License along with the GNU C Library; if not, see
++ <https://www.gnu.org/licenses/>. */
++
++#include <errno.h>
++#include <fcntl.h>
++#include <intprops.h>
++#include <limits.h>
++#include <stdio.h>
++#include <stdlib.h>
++#include <string.h>
++#include <sys/mount.h>
++#include <sys/stat.h>
++#include <sys/types.h>
++#include <sys/wait.h>
++
++#include <sys/socket.h>
++#include <sys/un.h>
++#include <support/check.h>
++#include <support/temp_file.h>
++#include <support/xsched.h>
++#include <support/xunistd.h>
++
++static char *base;
++#define BASENAME "tst-getcwd-smallbuff"
++#define MOUNT_NAME "mpoint"
++static int sockfd[2];
++
++static void
++do_cleanup (void)
++{
++ support_chdir_toolong_temp_directory (base);
++ TEST_VERIFY_EXIT (rmdir (MOUNT_NAME) == 0);
++ free (base);
++}
++
++static void
++send_fd (const int sock, const int fd)
++{
++ struct msghdr msg = {0};
++ union
++ {
++ struct cmsghdr hdr;
++ char buf[CMSG_SPACE (sizeof (int))];
++ } cmsgbuf = {0};
++ struct cmsghdr *cmsg;
++ struct iovec vec;
++ char ch = 'A';
++ ssize_t n;
++
++ msg.msg_control = &cmsgbuf.buf;
++ msg.msg_controllen = sizeof (cmsgbuf.buf);
++
++ cmsg = CMSG_FIRSTHDR (&msg);
++ cmsg->cmsg_len = CMSG_LEN (sizeof (int));
++ cmsg->cmsg_level = SOL_SOCKET;
++ cmsg->cmsg_type = SCM_RIGHTS;
++ memcpy (CMSG_DATA (cmsg), &fd, sizeof (fd));
++
++ vec.iov_base = &ch;
++ vec.iov_len = 1;
++ msg.msg_iov = &vec;
++ msg.msg_iovlen = 1;
++
++ while ((n = sendmsg (sock, &msg, 0)) == -1 && errno == EINTR);
++
++ TEST_VERIFY_EXIT (n == 1);
++}
++
++static int
++recv_fd (const int sock)
++{
++ struct msghdr msg = {0};
++ union
++ {
++ struct cmsghdr hdr;
++ char buf[CMSG_SPACE(sizeof(int))];
++ } cmsgbuf = {0};
++ struct cmsghdr *cmsg;
++ struct iovec vec;
++ ssize_t n;
++ char ch = '\0';
++ int fd = -1;
++
++ vec.iov_base = &ch;
++ vec.iov_len = 1;
++ msg.msg_iov = &vec;
++ msg.msg_iovlen = 1;
++
++ msg.msg_control = &cmsgbuf.buf;
++ msg.msg_controllen = sizeof (cmsgbuf.buf);
++
++ while ((n = recvmsg (sock, &msg, 0)) == -1 && errno == EINTR);
++ if (n != 1 || ch != 'A')
++ return -1;
++
++ cmsg = CMSG_FIRSTHDR (&msg);
++ if (cmsg == NULL)
++ return -1;
++ if (cmsg->cmsg_type != SCM_RIGHTS)
++ return -1;
++ memcpy (&fd, CMSG_DATA (cmsg), sizeof (fd));
++ if (fd < 0)
++ return -1;
++ return fd;
++}
++
++static int
++child_func (void * const arg)
++{
++ xclose (sockfd[0]);
++ const int sock = sockfd[1];
++ char ch;
++
++ TEST_VERIFY_EXIT (read (sock, &ch, 1) == 1);
++ TEST_VERIFY_EXIT (ch == '1');
++
++ if (mount ("/", MOUNT_NAME, NULL, MS_BIND | MS_REC, NULL))
++ FAIL_EXIT1 ("mount failed: %m\n");
++ const int fd = xopen ("mpoint",
++ O_RDONLY | O_PATH | O_DIRECTORY | O_NOFOLLOW, 0);
++
++ send_fd (sock, fd);
++ xclose (fd);
++
++ TEST_VERIFY_EXIT (read (sock, &ch, 1) == 1);
++ TEST_VERIFY_EXIT (ch == 'a');
++
++ xclose (sock);
++ return 0;
++}
++
++static void
++update_map (char * const mapping, const char * const map_file)
++{
++ const size_t map_len = strlen (mapping);
++
++ const int fd = xopen (map_file, O_WRONLY, 0);
++ xwrite (fd, mapping, map_len);
++ xclose (fd);
++}
++
++static void
++proc_setgroups_write (const long child_pid, const char * const str)
++{
++ const size_t str_len = strlen(str);
++
++ char setgroups_path[sizeof ("/proc//setgroups") + INT_STRLEN_BOUND (long)];
++
++ snprintf (setgroups_path, sizeof (setgroups_path),
++ "/proc/%ld/setgroups", child_pid);
++
++ const int fd = open (setgroups_path, O_WRONLY);
++
++ if (fd < 0)
++ {
++ TEST_VERIFY_EXIT (errno == ENOENT);
++ FAIL_UNSUPPORTED ("/proc/%ld/setgroups not found\n", child_pid);
++ }
++
++ xwrite (fd, str, str_len);
++ xclose(fd);
++}
++
++static char child_stack[1024 * 1024];
++
++int
++do_test (void)
++{
++ base = support_create_and_chdir_toolong_temp_directory (BASENAME);
++
++ xmkdir (MOUNT_NAME, S_IRWXU);
++ atexit (do_cleanup);
++
++ TEST_VERIFY_EXIT (socketpair (AF_UNIX, SOCK_STREAM, 0, sockfd) == 0);
++ pid_t child_pid = xclone (child_func, NULL, child_stack,
++ sizeof (child_stack),
++ CLONE_NEWUSER | CLONE_NEWNS | SIGCHLD);
++
++ xclose (sockfd[1]);
++ const int sock = sockfd[0];
++
++ char map_path[sizeof ("/proc//uid_map") + INT_STRLEN_BOUND (long)];
++ char map_buf[sizeof ("0 1") + INT_STRLEN_BOUND (long)];
++
++ snprintf (map_path, sizeof (map_path), "/proc/%ld/uid_map",
++ (long) child_pid);
++ snprintf (map_buf, sizeof (map_buf), "0 %ld 1", (long) getuid());
++ update_map (map_buf, map_path);
++
++ proc_setgroups_write ((long) child_pid, "deny");
++ snprintf (map_path, sizeof (map_path), "/proc/%ld/gid_map",
++ (long) child_pid);
++ snprintf (map_buf, sizeof (map_buf), "0 %ld 1", (long) getgid());
++ update_map (map_buf, map_path);
++
++ TEST_VERIFY_EXIT (send (sock, "1", 1, MSG_NOSIGNAL) == 1);
++ const int fd = recv_fd (sock);
++ TEST_VERIFY_EXIT (fd >= 0);
++ TEST_VERIFY_EXIT (fchdir (fd) == 0);
++
++ static char buf[2 * 10 + 1];
++ memset (buf, 'A', sizeof (buf));
++
++ /* Finally, call getcwd and check if it resulted in a buffer underflow. */
++ char * cwd = getcwd (buf + sizeof (buf) / 2, 1);
++ TEST_VERIFY (cwd == NULL);
++ TEST_VERIFY (errno == ERANGE);
++
++ for (int i = 0; i < sizeof (buf); i++)
++ if (buf[i] != 'A')
++ {
++ printf ("buf[%d] = %02x\n", i, (unsigned int) buf[i]);
++ support_record_failure ();
++ }
++
++ TEST_VERIFY_EXIT (send (sock, "a", 1, MSG_NOSIGNAL) == 1);
++ xclose (sock);
++ TEST_VERIFY_EXIT (xwaitpid (child_pid, NULL, 0) == child_pid);
++
++ return 0;
++}
++
++#define CLEANUP_HANDLER do_cleanup
++#include <support/test-driver.c>
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