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[glibc/release/2.29/master] elf: Fix pldd (BZ#18035)
- From: Florian Weimer <fw at sourceware dot org>
- To: glibc-cvs at sourceware dot org
- Date: 26 Apr 2019 12:42:10 -0000
- Subject: [glibc/release/2.29/master] elf: Fix pldd (BZ#18035)
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=eaea1dfbe95a31c29adc259100569962cddb6f19
commit eaea1dfbe95a31c29adc259100569962cddb6f19
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Fri Apr 26 13:58:31 2019 +0200
elf: Fix pldd (BZ#18035)
Since 9182aa67994 (Fix vDSO l_name for GDB's, BZ#387) the initial link_map
for executable itself and loader will have both l_name and l_libname->name
holding the same value due:
elf/dl-object.c
95 new->l_name = *realname ? realname : (char *) newname->name + libname_len - 1;
Since newname->name points to new->l_libname->name.
This leads to pldd to an infinite call at:
elf/pldd-xx.c
203 again:
204 while (1)
205 {
206 ssize_t n = pread64 (memfd, tmpbuf.data, tmpbuf.length, name_offset);
228 /* Try the l_libname element. */
229 struct E(libname_list) ln;
230 if (pread64 (memfd, &ln, sizeof (ln), m.l_libname) == sizeof (ln))
231 {
232 name_offset = ln.name;
233 goto again;
234 }
Since the value at ln.name (l_libname->name) will be the same as previously
read. The straightforward fix is just avoid the check and read the new list
entry.
I checked also against binaries issues with old loaders with fix for BZ#387,
and pldd could dump the shared objects.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, and
powerpc64le-linux-gnu.
[BZ #18035]
* elf/Makefile (tests-container): Add tst-pldd.
* elf/pldd-xx.c: Use _Static_assert in of pldd_assert.
(E(find_maps)): Avoid use alloca, use default read file operations
instead of explicit LFS names, and fix infinite loop.
* elf/pldd.c: Explicit set _FILE_OFFSET_BITS, cleanup headers.
(get_process_info): Use _Static_assert instead of assert, use default
directory operations instead of explicit LFS names, and free some
leadek pointers.
* elf/tst-pldd.c: New file.
(cherry picked from commit 1a4c27355e146b6d8cc6487b998462c7fdd1048f)
Diff:
---
ChangeLog | 13 +++++++
NEWS | 1 +
elf/Makefile | 1 +
elf/pldd-xx.c | 114 +++++++++++++++++++------------------------------------
elf/pldd.c | 64 +++++++++++++++----------------
elf/tst-pldd.c | 118 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 203 insertions(+), 108 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 2524e25..5af8e27 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2019-04-23 Adhemerval Zanella <adhemerval.zanella@linaro.org>
+
+ [BZ #18035]
+ * elf/Makefile (tests-container): Add tst-pldd.
+ * elf/pldd-xx.c: Use _Static_assert in of pldd_assert.
+ (E(find_maps)): Avoid use alloca, use default read file operations
+ instead of explicit LFS names, and fix infinite loop.
+ * elf/pldd.c: Explicit set _FILE_OFFSET_BITS, cleanup headers.
+ (get_process_info): Use _Static_assert instead of assert, use default
+ directory operations instead of explicit LFS names, and free some
+ leadek pointers.
+ * elf/tst-pldd.c: New file.
+
2019-04-17 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* support/Makefile (libsupport-routines): Add support_subprocess,
diff --git a/NEWS b/NEWS
index 117646d..b39a0cc 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ Major new features:
The following bugs are resolved with this release:
[16573] malloc: Set and reset all hooks for tracing
+ [18035] Fix pldd hang
[24155] x32 memcmp can treat positive length as 0 (if sign bit in RDX is set) (CVE-2019-7309)
[24164] Systemtap probes need to use "nr" constraint on 32-bit Arm
[24161] __run_fork_handlers self-deadlocks in malloc/tst-mallocfork2
diff --git a/elf/Makefile b/elf/Makefile
index 9cf5cd8..e7457e8 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -194,6 +194,7 @@ tests-internal += loadtest unload unload2 circleload1 \
tst-tls3 tst-tls6 tst-tls7 tst-tls8 tst-dlmopen2 \
tst-ptrguard1 tst-stackguard1 tst-libc_dlvsym \
tst-create_format1
+tests-container += tst-pldd
ifeq ($(build-hardcoded-path-in-tests),yes)
tests += tst-dlopen-aout
tst-dlopen-aout-no-pie = yes
diff --git a/elf/pldd-xx.c b/elf/pldd-xx.c
index 547f840..756f6d7 100644
--- a/elf/pldd-xx.c
+++ b/elf/pldd-xx.c
@@ -23,10 +23,6 @@
#define EW_(e, w, t) EW__(e, w, _##t)
#define EW__(e, w, t) e##w##t
-#define pldd_assert(name, exp) \
- typedef int __assert_##name[((exp) != 0) - 1]
-
-
struct E(link_map)
{
EW(Addr) l_addr;
@@ -39,12 +35,12 @@ struct E(link_map)
EW(Addr) l_libname;
};
#if CLASS == __ELF_NATIVE_CLASS
-pldd_assert (l_addr, (offsetof (struct link_map, l_addr)
- == offsetof (struct E(link_map), l_addr)));
-pldd_assert (l_name, (offsetof (struct link_map, l_name)
- == offsetof (struct E(link_map), l_name)));
-pldd_assert (l_next, (offsetof (struct link_map, l_next)
- == offsetof (struct E(link_map), l_next)));
+_Static_assert (offsetof (struct link_map, l_addr)
+ == offsetof (struct E(link_map), l_addr), "l_addr");
+_Static_assert (offsetof (struct link_map, l_name)
+ == offsetof (struct E(link_map), l_name), "l_name");
+_Static_assert (offsetof (struct link_map, l_next)
+ == offsetof (struct E(link_map), l_next), "l_next");
#endif
@@ -54,10 +50,10 @@ struct E(libname_list)
EW(Addr) next;
};
#if CLASS == __ELF_NATIVE_CLASS
-pldd_assert (name, (offsetof (struct libname_list, name)
- == offsetof (struct E(libname_list), name)));
-pldd_assert (next, (offsetof (struct libname_list, next)
- == offsetof (struct E(libname_list), next)));
+_Static_assert (offsetof (struct libname_list, name)
+ == offsetof (struct E(libname_list), name), "name");
+_Static_assert (offsetof (struct libname_list, next)
+ == offsetof (struct E(libname_list), next), "next");
#endif
struct E(r_debug)
@@ -69,16 +65,17 @@ struct E(r_debug)
EW(Addr) r_map;
};
#if CLASS == __ELF_NATIVE_CLASS
-pldd_assert (r_version, (offsetof (struct r_debug, r_version)
- == offsetof (struct E(r_debug), r_version)));
-pldd_assert (r_map, (offsetof (struct r_debug, r_map)
- == offsetof (struct E(r_debug), r_map)));
+_Static_assert (offsetof (struct r_debug, r_version)
+ == offsetof (struct E(r_debug), r_version), "r_version");
+_Static_assert (offsetof (struct r_debug, r_map)
+ == offsetof (struct E(r_debug), r_map), "r_map");
#endif
static int
-E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)
+E(find_maps) (const char *exe, int memfd, pid_t pid, void *auxv,
+ size_t auxv_size)
{
EW(Addr) phdr = 0;
unsigned int phnum = 0;
@@ -104,12 +101,9 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)
if (phdr == 0 || phnum == 0 || phent == 0)
error (EXIT_FAILURE, 0, gettext ("cannot find program header of process"));
- EW(Phdr) *p = alloca (phnum * phent);
- if (pread64 (memfd, p, phnum * phent, phdr) != phnum * phent)
- {
- error (0, 0, gettext ("cannot read program header"));
- return EXIT_FAILURE;
- }
+ EW(Phdr) *p = xmalloc (phnum * phent);
+ if (pread (memfd, p, phnum * phent, phdr) != phnum * phent)
+ error (EXIT_FAILURE, 0, gettext ("cannot read program header"));
/* Determine the load offset. We need this for interpreting the
other program header entries so we do this in a separate loop.
@@ -129,24 +123,18 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)
if (p[i].p_type == PT_DYNAMIC)
{
EW(Dyn) *dyn = xmalloc (p[i].p_filesz);
- if (pread64 (memfd, dyn, p[i].p_filesz, offset + p[i].p_vaddr)
+ if (pread (memfd, dyn, p[i].p_filesz, offset + p[i].p_vaddr)
!= p[i].p_filesz)
- {
- error (0, 0, gettext ("cannot read dynamic section"));
- return EXIT_FAILURE;
- }
+ error (EXIT_FAILURE, 0, gettext ("cannot read dynamic section"));
/* Search for the DT_DEBUG entry. */
for (unsigned int j = 0; j < p[i].p_filesz / sizeof (EW(Dyn)); ++j)
if (dyn[j].d_tag == DT_DEBUG && dyn[j].d_un.d_ptr != 0)
{
struct E(r_debug) r;
- if (pread64 (memfd, &r, sizeof (r), dyn[j].d_un.d_ptr)
+ if (pread (memfd, &r, sizeof (r), dyn[j].d_un.d_ptr)
!= sizeof (r))
- {
- error (0, 0, gettext ("cannot read r_debug"));
- return EXIT_FAILURE;
- }
+ error (EXIT_FAILURE, 0, gettext ("cannot read r_debug"));
if (r.r_map != 0)
{
@@ -160,13 +148,10 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)
}
else if (p[i].p_type == PT_INTERP)
{
- interp = alloca (p[i].p_filesz);
- if (pread64 (memfd, interp, p[i].p_filesz, offset + p[i].p_vaddr)
+ interp = xmalloc (p[i].p_filesz);
+ if (pread (memfd, interp, p[i].p_filesz, offset + p[i].p_vaddr)
!= p[i].p_filesz)
- {
- error (0, 0, gettext ("cannot read program interpreter"));
- return EXIT_FAILURE;
- }
+ error (EXIT_FAILURE, 0, gettext ("cannot read program interpreter"));
}
if (list == 0)
@@ -174,14 +159,16 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)
if (interp == NULL)
{
// XXX check whether the executable itself is the loader
- return EXIT_FAILURE;
+ exit (EXIT_FAILURE);
}
// XXX perhaps try finding ld.so and _r_debug in it
-
- return EXIT_FAILURE;
+ exit (EXIT_FAILURE);
}
+ free (p);
+ free (interp);
+
/* Print the PID and program name first. */
printf ("%lu:\t%s\n", (unsigned long int) pid, exe);
@@ -192,47 +179,27 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)
do
{
struct E(link_map) m;
- if (pread64 (memfd, &m, sizeof (m), list) != sizeof (m))
- {
- error (0, 0, gettext ("cannot read link map"));
- status = EXIT_FAILURE;
- goto out;
- }
+ if (pread (memfd, &m, sizeof (m), list) != sizeof (m))
+ error (EXIT_FAILURE, 0, gettext ("cannot read link map"));
EW(Addr) name_offset = m.l_name;
- again:
while (1)
{
- ssize_t n = pread64 (memfd, tmpbuf.data, tmpbuf.length, name_offset);
+ ssize_t n = pread (memfd, tmpbuf.data, tmpbuf.length, name_offset);
if (n == -1)
- {
- error (0, 0, gettext ("cannot read object name"));
- status = EXIT_FAILURE;
- goto out;
- }
+ error (EXIT_FAILURE, 0, gettext ("cannot read object name"));
if (memchr (tmpbuf.data, '\0', n) != NULL)
break;
if (!scratch_buffer_grow (&tmpbuf))
- {
- error (0, 0, gettext ("cannot allocate buffer for object name"));
- status = EXIT_FAILURE;
- goto out;
- }
+ error (EXIT_FAILURE, 0,
+ gettext ("cannot allocate buffer for object name"));
}
- if (((char *)tmpbuf.data)[0] == '\0' && name_offset == m.l_name
- && m.l_libname != 0)
- {
- /* Try the l_libname element. */
- struct E(libname_list) ln;
- if (pread64 (memfd, &ln, sizeof (ln), m.l_libname) == sizeof (ln))
- {
- name_offset = ln.name;
- goto again;
- }
- }
+ /* The m.l_name and m.l_libname.name for loader linkmap points to same
+ values (since BZ#387 fix). Trying to use l_libname name as the
+ shared object name might lead to an infinite loop (BZ#18035). */
/* Skip over the executable. */
if (((char *)tmpbuf.data)[0] != '\0')
@@ -242,7 +209,6 @@ E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)
}
while (list != 0);
- out:
scratch_buffer_free (&tmpbuf);
return status;
}
diff --git a/elf/pldd.c b/elf/pldd.c
index f3fac4e..69629bd 100644
--- a/elf/pldd.c
+++ b/elf/pldd.c
@@ -17,23 +17,17 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <alloca.h>
+#define _FILE_OFFSET_BITS 64
+
#include <argp.h>
-#include <assert.h>
#include <dirent.h>
-#include <elf.h>
-#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <libintl.h>
-#include <link.h>
-#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
-#include <string.h>
#include <unistd.h>
#include <sys/ptrace.h>
-#include <sys/stat.h>
#include <sys/wait.h>
#include <scratch_buffer.h>
@@ -76,14 +70,9 @@ static struct argp argp =
options, parse_opt, args_doc, doc, NULL, more_help, NULL
};
-// File descriptor of /proc/*/mem file.
-static int memfd;
-
-/* Name of the executable */
-static char *exe;
/* Local functions. */
-static int get_process_info (int dfd, long int pid);
+static int get_process_info (const char *exe, int dfd, long int pid);
static void wait_for_ptrace_stop (long int pid);
@@ -102,8 +91,10 @@ main (int argc, char *argv[])
return 1;
}
- assert (sizeof (pid_t) == sizeof (int)
- || sizeof (pid_t) == sizeof (long int));
+ _Static_assert (sizeof (pid_t) == sizeof (int)
+ || sizeof (pid_t) == sizeof (long int),
+ "sizeof (pid_t) != sizeof (int) or sizeof (long int)");
+
char *endp;
errno = 0;
long int pid = strtol (argv[remaining], &endp, 10);
@@ -119,25 +110,24 @@ main (int argc, char *argv[])
if (dfd == -1)
error (EXIT_FAILURE, errno, gettext ("cannot open %s"), buf);
- struct scratch_buffer exebuf;
- scratch_buffer_init (&exebuf);
+ /* Name of the executable */
+ struct scratch_buffer exe;
+ scratch_buffer_init (&exe);
ssize_t nexe;
while ((nexe = readlinkat (dfd, "exe",
- exebuf.data, exebuf.length)) == exebuf.length)
+ exe.data, exe.length)) == exe.length)
{
- if (!scratch_buffer_grow (&exebuf))
+ if (!scratch_buffer_grow (&exe))
{
nexe = -1;
break;
}
}
if (nexe == -1)
- exe = (char *) "<program name undetermined>";
+ /* Default stack allocation is at least 1024. */
+ snprintf (exe.data, exe.length, "<program name undetermined>");
else
- {
- exe = exebuf.data;
- exe[nexe] = '\0';
- }
+ ((char*)exe.data)[nexe] = '\0';
/* Stop all threads since otherwise the list of loaded modules might
change while we are reading it. */
@@ -155,8 +145,8 @@ main (int argc, char *argv[])
error (EXIT_FAILURE, errno, gettext ("cannot prepare reading %s/task"),
buf);
- struct dirent64 *d;
- while ((d = readdir64 (dir)) != NULL)
+ struct dirent *d;
+ while ((d = readdir (dir)) != NULL)
{
if (! isdigit (d->d_name[0]))
continue;
@@ -182,7 +172,7 @@ main (int argc, char *argv[])
wait_for_ptrace_stop (tid);
- struct thread_list *newp = alloca (sizeof (*newp));
+ struct thread_list *newp = xmalloc (sizeof (*newp));
newp->tid = tid;
newp->next = thread_list;
thread_list = newp;
@@ -190,17 +180,22 @@ main (int argc, char *argv[])
closedir (dir);
- int status = get_process_info (dfd, pid);
+ if (thread_list == NULL)
+ error (EXIT_FAILURE, 0, gettext ("no valid %s/task entries"), buf);
+
+ int status = get_process_info (exe.data, dfd, pid);
- assert (thread_list != NULL);
do
{
ptrace (PTRACE_DETACH, thread_list->tid, NULL, NULL);
+ struct thread_list *prev = thread_list;
thread_list = thread_list->next;
+ free (prev);
}
while (thread_list != NULL);
close (dfd);
+ scratch_buffer_free (&exe);
return status;
}
@@ -281,9 +276,10 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
static int
-get_process_info (int dfd, long int pid)
+get_process_info (const char *exe, int dfd, long int pid)
{
- memfd = openat (dfd, "mem", O_RDONLY);
+ /* File descriptor of /proc/<pid>/mem file. */
+ int memfd = openat (dfd, "mem", O_RDONLY);
if (memfd == -1)
goto no_info;
@@ -333,9 +329,9 @@ get_process_info (int dfd, long int pid)
int retval;
if (e_ident[EI_CLASS] == ELFCLASS32)
- retval = find_maps32 (pid, auxv, auxv_size);
+ retval = find_maps32 (exe, memfd, pid, auxv, auxv_size);
else
- retval = find_maps64 (pid, auxv, auxv_size);
+ retval = find_maps64 (exe, memfd, pid, auxv, auxv_size);
free (auxv);
close (memfd);
diff --git a/elf/tst-pldd.c b/elf/tst-pldd.c
new file mode 100644
index 0000000..ed19ced
--- /dev/null
+++ b/elf/tst-pldd.c
@@ -0,0 +1,118 @@
+/* Basic tests for pldd program.
+ Copyright (C) 2019 Free Software Foundation, Inc.
+ 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <libgen.h>
+#include <stdbool.h>
+
+#include <array_length.h>
+#include <gnu/lib-names.h>
+
+#include <support/subprocess.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+
+static void
+target_process (void *arg)
+{
+ pause ();
+}
+
+/* The test runs in a container because pldd does not support tracing
+ a binary started by the loader iself (as with testrun.sh). */
+
+static int
+do_test (void)
+{
+ /* Create a copy of current test to check with pldd. */
+ struct support_subprocess target = support_subprocess (target_process, NULL);
+
+ /* Run 'pldd' on test subprocess. */
+ struct support_capture_subprocess pldd;
+ {
+ /* Three digits per byte plus null terminator. */
+ char pid[3 * sizeof (uint32_t) + 1];
+ snprintf (pid, array_length (pid), "%d", target.pid);
+
+ const char prog[] = "/usr/bin/pldd";
+
+ pldd = support_capture_subprogram (prog,
+ (char *const []) { (char *) prog, pid, NULL });
+
+ support_capture_subprocess_check (&pldd, "pldd", 0, sc_allow_stdout);
+ }
+
+ /* Check 'pldd' output. The test is expected to be linked against only
+ loader and libc. */
+ {
+ pid_t pid;
+ char buffer[512];
+#define STRINPUT(size) "%" # size "s"
+
+ FILE *out = fmemopen (pldd.out.buffer, pldd.out.length, "r");
+ TEST_VERIFY (out != NULL);
+
+ /* First line is in the form of <pid>: <full path of executable> */
+ TEST_COMPARE (fscanf (out, "%u: " STRINPUT (512), &pid, buffer), 2);
+
+ TEST_COMPARE (pid, target.pid);
+ TEST_COMPARE (strcmp (basename (buffer), "tst-pldd"), 0);
+
+ /* It expects only one loader and libc loaded by the program. */
+ bool interpreter_found = false, libc_found = false;
+ while (fgets (buffer, array_length (buffer), out) != NULL)
+ {
+ /* Ignore vDSO. */
+ if (buffer[0] != '/')
+ continue;
+
+ /* Remove newline so baseline (buffer) can compare against the
+ LD_SO and LIBC_SO macros unmodified. */
+ if (buffer[strlen(buffer)-1] == '\n')
+ buffer[strlen(buffer)-1] = '\0';
+
+ if (strcmp (basename (buffer), LD_SO) == 0)
+ {
+ TEST_COMPARE (interpreter_found, false);
+ interpreter_found = true;
+ continue;
+ }
+
+ if (strcmp (basename (buffer), LIBC_SO) == 0)
+ {
+ TEST_COMPARE (libc_found, false);
+ libc_found = true;
+ continue;
+ }
+ }
+ TEST_COMPARE (interpreter_found, true);
+ TEST_COMPARE (libc_found, true);
+
+ fclose (out);
+ }
+
+ support_capture_subprocess_free (&pldd);
+ support_process_terminate (&target);
+
+ return 0;
+}
+
+#include <support/test-driver.c>