@@ -145,11 +145,16 @@ __libc_setup_tls (void)
_dl_allocate_tls_storage (in elf/dl-tls.c) does using __libc_memalign
and dl_tls_static_align. */
tcb_offset = roundup (memsz + GLRO(dl_tls_static_surplus), max_align);
- tlsblock = __sbrk (tcb_offset + TLS_INIT_TCB_SIZE + max_align);
+ tlsblock = _dl_early_allocate (tcb_offset + TLS_INIT_TCB_SIZE + max_align);
+ if (tlsblock == NULL)
+ _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n");
#elif TLS_DTV_AT_TP
tcb_offset = roundup (TLS_INIT_TCB_SIZE, align ?: 1);
- tlsblock = __sbrk (tcb_offset + memsz + max_align
- + TLS_PRE_TCB_SIZE + GLRO(dl_tls_static_surplus));
+ tlsblock = _dl_early_allocate (tcb_offset + memsz + max_align
+ + TLS_PRE_TCB_SIZE
+ + GLRO(dl_tls_static_surplus));
+ if (tlsblock == NULL)
+ _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n");
tlsblock += TLS_PRE_TCB_SIZE;
#else
/* In case a model with a different layout for the TCB and DTV
@@ -157,6 +162,7 @@ __libc_setup_tls (void)
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
#endif
+
/* Align the TLS block. */
tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
& ~(max_align - 1));
@@ -33,6 +33,7 @@ routines = \
$(all-dl-routines) \
dl-addr \
dl-addr-obj \
+ dl-early_allocate \
dl-error \
dl-iteratephdr \
dl-libc \
@@ -108,6 +109,7 @@ all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
# But they are absent from the shared libc, because that code is in ld.so.
elide-routines.os = \
$(all-dl-routines) \
+ dl-early_allocate \
dl-exception \
dl-origin \
dl-reloc-static-pie \
@@ -276,6 +278,7 @@ tests-static-normal := \
tst-linkall-static \
tst-single_threaded-pthread-static \
tst-single_threaded-static \
+ tst-tls-allocation-failure-static \
tst-tlsalign-extern-static \
tst-tlsalign-static \
# tests-static-normal
@@ -1213,6 +1216,10 @@ $(objpfx)tst-glibcelf.out: tst-glibcelf.py elf.h $(..)/scripts/glibcelf.py \
--cc="$(CC) $(patsubst -DMODULE_NAME=%,-DMODULE_NAME=testsuite,$(CPPFLAGS))" \
< /dev/null > $@ 2>&1; $(evaluate-test)
+ifeq ($(run-built-tests),yes)
+tests-special += $(objpfx)tst-tls-allocation-failure-static-patched.out
+endif
+
# The test requires shared _and_ PIE because the executable
# unit test driver must be able to link with the shared object
# that is going to eventually go into an installed DSO.
@@ -2937,3 +2944,15 @@ $(eval $(call tst-trace-skeleton,4,\
$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4))
$(eval $(call tst-trace-skeleton,5,\
$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4:$(objpfx)libtracemod5))
+
+$(objpfx)tst-tls-allocation-failure-static-patched: \
+ $(objpfx)tst-tls-allocation-failure-static $(..)scripts/tst-elf-edit.py
+ cp $< $@
+ $(PYTHON) $(..)scripts/tst-elf-edit.py --maximize-tls-size $@
+
+$(objpfx)tst-tls-allocation-failure-static-patched.out: \
+ $(objpfx)tst-tls-allocation-failure-static-patched
+ $< > $@ 2>&1; echo "status: $$?" >> $@
+ grep -q '^Fatal glibc error: Cannot allocate TLS block$$' $@ \
+ && grep -q '^status: 127$$' $@; \
+ $(evaluate-test)
new file mode 100644
@@ -0,0 +1,30 @@
+/* Early memory allocation for the dynamic loader. Generic version.
+ Copyright (C) 2022 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/>. */
+
+#include <ldsodefs.h>
+#include <stddef.h>
+#include <unistd.h>
+
+void *
+_dl_early_allocate (size_t size)
+{
+ void *result = __sbrk (size);
+ if (result == (void *) -1)
+ _dl_fatal_printf ("Fatal glibc error: Early memory allocation failed\n");
+ return result;
+}
new file mode 100644
@@ -0,0 +1,31 @@
+/* Base for test program with impossiblyh large PT_TLS segment.
+ Copyright (C) 2022 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 test actual binary is patched using scripts/tst-elf-edit.py
+ --maximize-tls-size, and this introduces the expected test
+ allocation failure due to an excessive PT_LS p_memsz value.
+
+ Patching the binary is required because on some 64-bit targets, TLS
+ relocations can only cover a 32-bit range, and glibc-internal TLS
+ variables such as errno end up outside that range. */
+
+int
+main (void)
+{
+ return 0;
+}
@@ -43,9 +43,11 @@ EI_DATA=5
ELFDATA2LSB=b'\x01'
ELFDATA2MSB=b'\x02'
+ET_EXEC=2
ET_DYN=3
PT_LOAD=1
+PT_TLS=7
def elf_types_fmts(e_ident):
endian = '<' if e_ident[EI_DATA] == ELFDATA2LSB else '>'
@@ -146,8 +148,15 @@ def elf_edit_align(phdr, align):
else:
phdr.p_align = int(align)
+def elf_edit_maximize_tls_size(phdr, elfclass):
+ if elfclass == ELFCLASS32:
+ # It is possible that the kernel can allocate half of the
+ # address space, so use something larger.
+ phdr.p_memsz = 0xfff00000
+ else:
+ phdr.p_memsz = 1 << 63
-def elf_edit(f, align):
+def elf_edit(f, opts):
ei_nident_fmt = 'c' * EI_NIDENT
ei_nident_len = struct.calcsize(ei_nident_fmt)
@@ -172,24 +181,35 @@ def elf_edit(f, align):
ehdr = Elf_Ehdr(e_ident)
ehdr.read(f)
- if ehdr.e_type != ET_DYN:
- error('{}: not a shared library'.format(f.name))
+ if ehdr.e_type not in (ET_EXEC, ET_DYN):
+ error('{}: not an executable or shared library'.format(f.name))
phdr = Elf_Phdr(e_ident)
+ maximize_tls_size_done = False
for i in range(0, ehdr.e_phnum):
f.seek(ehdr.e_phoff + i * phdr.len)
phdr.read(f)
- if phdr.p_type == PT_LOAD:
- elf_edit_align(phdr, align)
+ if phdr.p_type == PT_LOAD and opts.align is not None:
+ elf_edit_align(phdr, opts.align)
+ f.seek(ehdr.e_phoff + i * phdr.len)
+ phdr.write(f)
+ break
+ if phdr.p_type == PT_TLS and opts.maximize_tls_size:
+ elf_edit_maximize_tls_size(phdr, e_ident[EI_CLASS])
f.seek(ehdr.e_phoff + i * phdr.len)
phdr.write(f)
+ maximize_tls_size_done = True
break
+ if opts.maximize_tls_size and not maximize_tls_size_done:
+ error('{}: TLS maximum size was not updated'.format(f.name))
def get_parser():
parser = argparse.ArgumentParser(description=__doc__)
- parser.add_argument('-a', dest='align', required=True,
+ parser.add_argument('-a', dest='align',
help='How to set the LOAD alignment')
+ parser.add_argument('--maximize-tls-size', action='store_true',
+ help='Set maximum PT_TLS size')
parser.add_argument('output',
help='ELF file to edit')
return parser
@@ -199,7 +219,7 @@ def main(argv):
parser = get_parser()
opts = parser.parse_args(argv)
with open(opts.output, 'r+b') as fout:
- elf_edit(fout, opts.align)
+ elf_edit(fout, opts)
if __name__ == '__main__':
@@ -1211,6 +1211,11 @@ extern struct link_map * _dl_get_dl_main_map (void)
# endif
#endif
+/* Perform early memory allocation, avoding a TCB dependency.
+ Terminate the process if allocation fails. May attempt to use
+ brk. */
+void *_dl_early_allocate (size_t size) attribute_hidden;
+
/* Initialize the DSO sort algorithm to use. */
#if !HAVE_TUNABLES
static inline void
new file mode 100644
@@ -0,0 +1,81 @@
+/* Early memory allocation for the dynamic loader. Generic version.
+ Copyright (C) 2022 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/>. */
+
+/* Mark symbols hidden in static PIE for early self relocation to work. */
+#if BUILD_PIE_DEFAULT
+# pragma GCC visibility push(hidden)
+#endif
+#include <startup.h>
+
+#include <ldsodefs.h>
+#include <stddef.h>
+#include <string.h>
+#include <sysdep.h>
+#include <unistd.h>
+
+#include <mmap_call.h>
+
+/* Defined in brk.c. */
+extern void *__curbrk;
+
+void *
+_dl_early_allocate (size_t size)
+{
+ void *result;
+
+ if (__curbrk != NULL)
+ /* If the break has been initialized, brk must have run before,
+ so just call it once more. */
+ {
+ result = __sbrk (size);
+ if (result == (void *) -1)
+ result = NULL;
+ }
+ else
+ {
+ /* If brk has not been invoked, there is no need to update
+ __curbrk. The first call to brk will take care of that. */
+ void *previous = (void *) INTERNAL_SYSCALL_CALL (brk, 0);
+ result = (void *) INTERNAL_SYSCALL_CALL (brk, previous + size);
+ if (result == previous)
+ result = NULL;
+ else
+ result = previous;
+ }
+
+ /* If brk fails, fall back to mmap. This can happen due to
+ unfortunate ASLR layout decisions and kernel bugs, particularly
+ for static PIE. */
+ if (result == NULL)
+ {
+ long int ret;
+ int prot = PROT_READ | PROT_WRITE;
+ int flags = MAP_PRIVATE | MAP_ANONYMOUS;
+#ifdef __NR_mmap2
+ ret = MMAP_CALL_INTERNAL (mmap2, 0, size, prot, flags, -1, 0);
+#else
+ ret = MMAP_CALL_INTERNAL (mmap, 0, size, prot, flags, -1, 0);
+#endif
+ if (INTERNAL_SYSCALL_ERROR_P (ret))
+ result = NULL;
+ else
+ result = (void *) ret;
+ }
+
+ return result;
+}