From 332421312576bd7095e70589154af99b124dd2d1 Mon Sep 17 00:00:00 2001
From: Carlos O'Donell <carlos@redhat.com>
Date: Fri, 12 Mar 2021 16:44:47 +0100
Subject: elf: Always set l in _dl_init_paths (bug 23462)
After d1d5471579eb0426671bf94f2d71e61dfb204c30 ("Remove dead
DL_DST_REQ_STATIC code.") we always setup the link map l to make the
static and shared cases the same. The bug is that in elf/dl-load.c
(_dl_init_paths) we conditionally set l only in the #ifdef SHARED
case, but unconditionally use it later. The simple solution is to
remove the #ifdef SHARED conditional, because it's no longer needed,
and unconditionally setup l for both the static and shared cases. A
regression test is added to run a static binary with
LD_LIBRARY_PATH='$ORIGIN' which crashes before the fix and runs after
the fix.
Co-Authored-By: Florian Weimer <fweimer@redhat.com>
diff --git a/elf/Makefile b/elf/Makefile
--- a/elf/Makefile 2021-11-02 16:28:14.720143774 -0400
+++ b/elf/Makefile 2021-11-02 18:42:38.763843571 -0400
@@ -151,7 +151,8 @@ endif
tests-static-normal := tst-leaks1-static tst-array1-static tst-array5-static \
tst-dl-iter-static \
tst-tlsalign-static tst-tlsalign-extern-static \
- tst-linkall-static tst-env-setuid tst-env-setuid-tunables
+ tst-linkall-static tst-env-setuid tst-env-setuid-tunables \
+ tst-dst-static
tests-static-internal := tst-tls1-static tst-tls2-static \
tst-ptrguard1-static tst-stackguard1-static \
tst-tls1-static-non-pie tst-libc_dlvsym-static
@@ -1811,3 +1812,5 @@ $(objpfx)tst-glibc-hwcaps-mask.out: \
# Generic dependency for sysdeps implementation of
# tst-glibc-hwcaps-cache.
$(objpfx)tst-glibc-hwcaps-cache.out: $(objpfx)tst-glibc-hwcaps
+
+tst-dst-static-ENV = LD_LIBRARY_PATH='$$ORIGIN'
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 9e2089cfaa..376a2e64d6 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -758,50 +758,45 @@ _dl_init_paths (const char *llp, const char *source,
max_dirnamelen = SYSTEM_DIRS_MAX_LEN;
*aelem = NULL;
-#ifdef SHARED
/* This points to the map of the main object. */
l = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
- if (l != NULL)
+ assert (l->l_type != lt_loaded);
+
+ if (l->l_info[DT_RUNPATH])
+ {
+ /* Allocate room for the search path and fill in information
+ from RUNPATH. */
+ decompose_rpath (&l->l_runpath_dirs,
+ (const void *) (D_PTR (l, l_info[DT_STRTAB])
+ + l->l_info[DT_RUNPATH]->d_un.d_val),
+ l, "RUNPATH");
+ /* During rtld init the memory is allocated by the stub malloc,
+ prevent any attempt to free it by the normal malloc. */
+ l->l_runpath_dirs.malloced = 0;
+
+ /* The RPATH is ignored. */
+ l->l_rpath_dirs.dirs = (void *) -1;
+ }
+ else
{
- assert (l->l_type != lt_loaded);
+ l->l_runpath_dirs.dirs = (void *) -1;
- if (l->l_info[DT_RUNPATH])
+ if (l->l_info[DT_RPATH])
{
/* Allocate room for the search path and fill in information
- from RUNPATH. */
- decompose_rpath (&l->l_runpath_dirs,
+ from RPATH. */
+ decompose_rpath (&l->l_rpath_dirs,
(const void *) (D_PTR (l, l_info[DT_STRTAB])
- + l->l_info[DT_RUNPATH]->d_un.d_val),
- l, "RUNPATH");
- /* During rtld init the memory is allocated by the stub malloc,
- prevent any attempt to free it by the normal malloc. */
- l->l_runpath_dirs.malloced = 0;
-
- /* The RPATH is ignored. */
- l->l_rpath_dirs.dirs = (void *) -1;
+ + l->l_info[DT_RPATH]->d_un.d_val),
+ l, "RPATH");
+ /* During rtld init the memory is allocated by the stub
+ malloc, prevent any attempt to free it by the normal
+ malloc. */
+ l->l_rpath_dirs.malloced = 0;
}
else
- {
- l->l_runpath_dirs.dirs = (void *) -1;
-
- if (l->l_info[DT_RPATH])
- {
- /* Allocate room for the search path and fill in information
- from RPATH. */
- decompose_rpath (&l->l_rpath_dirs,
- (const void *) (D_PTR (l, l_info[DT_STRTAB])
- + l->l_info[DT_RPATH]->d_un.d_val),
- l, "RPATH");
- /* During rtld init the memory is allocated by the stub
- malloc, prevent any attempt to free it by the normal
- malloc. */
- l->l_rpath_dirs.malloced = 0;
- }
- else
- l->l_rpath_dirs.dirs = (void *) -1;
- }
+ l->l_rpath_dirs.dirs = (void *) -1;
}
-#endif /* SHARED */
if (llp != NULL && *llp != '\0')
{
diff --git a/elf/tst-dst-static.c b/elf/tst-dst-static.c
new file mode 100644
index 0000000000..56eb371c96
--- /dev/null
+++ b/elf/tst-dst-static.c
@@ -0,0 +1,32 @@
+/* Test DST expansion for static binaries doesn't carsh. Bug 23462.
+ Copyright (C) 2021 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
+ <https://www.gnu.org/licenses/>. */
+
+/* The purpose of this test is to exercise the code in elf/dl-loac.c
+ (_dl_init_paths) or thereabout and ensure that static binaries
+ don't crash when expanding DSTs.
+
+ If the dynamic loader code linked into the static binary cannot
+ handle expanding the DSTs e.g. null-deref on an incomplete link
+ map, then it will crash before reaching main, so the test harness
+ is unnecessary. */
+
+int
+main (void)
+{
+ return 0;
+}