The last section in a CTF dict is the string table, at an offset
represented by the cth_stroff header field. Its length is recorded in
the next field, cth_strlen, and the two added together are taken as the
size of the CTF dict. Upon opening a dict, we check that none of the
header offsets exceed this size, and we check when uncompressing a
compressed dict that the result of the uncompression is the same length:
but CTF dicts need not be compressed, and short ones are not.
Uncompressed dicts just use the ctf_size without checking it. This
field is thankfully almost unused: it is mostly used when reserializing
a dict, which can't be done to dicts read off disk since they're
read-only.
However, when opening an uncompressed foreign-endian dict we have to
copy it out of the mmaped region it is stored in so we can endian-
swap it, and we use ctf_size when doing that. When the cth_strlen is
corrupt, this can overrun.
Fix this by checking the ctf_size in all uncompressed cases, just as we
already do in the compressed case. Add a new test.
This came to light because various corrupted-CTF raw-asm tests had an
incorrect cth_strlen: fix all of them so they produce the expected
error again.
libctf/
PR libctf/28933
* ctf-open.c (ctf_bufopen_internal): Always check uncompressed
CTF dict sizes against the section size in case the cth_strlen is
corrupt.
Without a -M cpu option given, powerpc objdump defaults currently to
-Mpower10 but -Many is also given. Commit 1ff6a3b8e562 regressed
-Many disassembly of instructions that are encoded differently
depending on cpu, such as mftb which has pre- and post-power4
encodings.
PR 28959
* ppc-dis.c (lookup_powerpc): Revert 2021-05-28 change. Instead
only look at deprecated PPC_OPCODE_RAW bit when -Many.
Alan Modra [Wed, 2 Mar 2022 13:34:57 +0000 (00:04 +1030)]
PowerPC64 DT_RELR relative reloc addresses
Section addresses can change between ppc64_elf_size_stubs and
ppc64_elf_build_stubs due to .eh_frame editing. The idea of stashing
r_offset final addresses calculated in ppc64_elf_size_stubs for use by
ppc64_elf_build_stubs was never a good idea. Instead, we need to keep
section/offset pairs.
* elf64-ppc.c (struct ppc_link_hash_table): Delete relr_addr.
Add relr section/offset array.
(append_relr_off): Rewrite. Update all callers.
(sort_relr): New function.
(ppc64_elf_size_stubs): Adjust to suit new relative reloc stash.
(ppc64_elf_build_stubs): Likewise.
Alan Modra [Wed, 9 Feb 2022 05:51:02 +0000 (16:21 +1030)]
Work around gcc-4 warnings in elf64-ppc.c
elf64-ppc.c: In function 'ppc64_elf_size_dynamic_sections':
elf64-ppc.c:10309:45: error: value computed is not used [-Werror=unused-value]
++lgot_ents, ++lgot_masks, isym != NULL && isym++)
It is of course a silly warning, fixed in later versions of gcc. I
wrote "isym != NULL && isym++" rather than the simpler "isym++" to
stop sanitisers complaining about incrementing a NULL pointer. isym
is of course unused in any code path where it might start off as
NULL. Sometimes you can't win. So don't try to be clever in reading
local symbols only when needed. 99 times out of 100 they will be
cached anyway.
* elf64-ppc.c (ppc64_elf_size_dynamic_sections): Avoid annoying
warnings by always reading local syms.
(ppc64_elf_layout_multitoc): Likewise.
H.J. Lu [Wed, 9 Feb 2022 23:51:22 +0000 (15:51 -0800)]
x86: Disallow invalid relocation against protected symbol
I am checking this into master and will backport it to 2.38 branch.
H.J
----
On x86, GCC 12 supports -mno-direct-extern-access to enable canonical
reference to protected function and disable copy relocation. With
-mno-direct-extern-access, the canonical protected function symbols must
be accessed via canonical reference and the protected data symbols in
shared libraries are non-copyable. Under glibc 2.35, non-canonical
reference to the canonical protected function will get the run-time error:
./y: internal_f: ./libfoo.so: non-canonical reference to canonical protected function
and copy relocations against the non-copyable protected symbols will get
the run-time error:
./x: internal_i: ./libfoo.so: copy relocation against non-copyable protected symbol
Update x86 linker to disallow non-canonical reference to the canonical
protected function:
ld: plt.o: non-canonical reference to canonical protected function `internal_f' in libfoo.so
ld: failed to set dynamic section sizes: bad value
and copy relocation against the non-copyable protected symbol:
ld: main.o: copy relocation against non-copyable protected symbol `internal_i' in libfoo.so
Palmer Dabbelt [Mon, 7 Feb 2022 20:14:30 +0000 (12:14 -0800)]
RISC-V: Stop reporting warnings for mismatched extension versions
The extension version checking logic is really just too complicated to
encode into the linker, trying to do so causes more harm than good.
This removes the checks and the associated tests, leaving the logic to
keep the largest version of each extension linked into the target.
bfd/
* elfnn-riscv.c (riscv_version_mismatch): Rename to
riscv_update_subset_version, and stop reporting warnings on
version mismatches.
(riscv_merge_std_ext): Adjust calls to riscv_version_mismatch.
(riscv_merge_multi_letter_ext): Likewise.
Alan Modra [Fri, 4 Feb 2022 09:00:47 +0000 (19:30 +1030)]
Detect .eh_frame_hdr earlier for SIZEOF_HEADERS
Current code detects the need for PT_GNU_EH_FRAME using a field set by
_bfd_elf_discard_section_eh_frame_hdr, which is called fairly late in
the linking process. Use the elf hash table eh_info instead, which is
set up earlier by size_dynamic_sections.
Alan Modra [Wed, 26 Jan 2022 00:01:36 +0000 (10:31 +1030)]
PowerPC64 treatment of absolute symbols
Supporting -static-pie on PowerPC64 requires the linker to properly
treat SHN_ABS symbols for cases like glibc's _nl_current_LC_CTYPE_used
absolute symbol. I've been slow to fix the linker on powerpc because
there is some chance that this will break some shared libraries or
PIEs.
bfd/
* elf64-ppc.c (ppc64_elf_check_relocs): Consolidate local sym
handling code. Don't count dyn relocs against non-dynamic
absolute symbols.
(dec_dynrel_count): Adjust to suit.
(ppc64_elf_edit_toc): Don't remove entries for absolute symbols
when pic.
(allocate_got): Don't allocate space for got relocs against
non-dynamic absolute syms.
(ppc64_elf_layout_multitoc): Likewise.
(got_and_plt_relr): Likewise.
(ppc64_elf_size_dynamic_sections): Likewise for local got.
(got_and_plt_relr_for_local_syms): Likewise.
(ppc64_elf_size_stubs): Don't allocate space for relr either.
(ppc64_elf_relocate_section): Don't write relocs against non-dynamic
absolute symbols. Don't optimise got and toc code sequences
loading absolute symbol entries.
ld/
* testsuite/ld-powerpc/abs-reloc.s,
* testsuite/ld-powerpc/abs-static.d,
* testsuite/ld-powerpc/abs-static.r,
* testsuite/ld-powerpc/abs-pie.d,
* testsuite/ld-powerpc/abs-pie.r,
* testsuite/ld-powerpc/abs-shared.d,
* testsuite/ld-powerpc/abs-shared.r,
* testsuite/ld-powerpc/abs-pie-relr.d,
* testsuite/ld-powerpc/abs-pie-relr.r,
* testsuite/ld-powerpc/abs-shared-relr.d,
* testsuite/ld-powerpc/abs-shared-relr.r: New tests.
* testsuite/ld-powerpc/powerpc.exp: Run them.
Alan Modra [Thu, 27 Jan 2022 23:16:13 +0000 (09:46 +1030)]
PR28827, assertion building LLVM 9 on powerpc64le-linux-gnu
The assertion is this one in ppc_build_one_stub
BFD_ASSERT (stub_entry->stub_offset >= stub_entry->group->stub_sec->size);
It is checking that a stub doesn't overwrite the tail of a previous
stub, so not something trivial.
Normally, stub sizing iterates until no stubs are added, detected by
no change in stub section size. Iteration also continues if no stubs
are added but one or more stubs increases in size, which also can be
detected by a change in stub section size. But there is a
pathological case where stub section sizing decreases one iteration
then increases the next. To handle that situation, stub sizing also
stops at more than STUB_SHRINK_ITER (20) iterations when calculated
stub section size is smaller. The previous larger size is kept for
the actual layout (so that building the stubs, which behaves like
another iteration of stub sizing, will see the stub section sizes
shrink). The problem with that stopping condition is that it assumes
that stub sizing is only affected by addresses external to the stub
sections, which isn't always true.
This patch fixes that by also keeping larger individual stub_offset
addresses past STUB_SHRINK_ITER. It also catches a further
pathological case where one stub shrinks and another expands in such a
way that no stub section size change is seen.
PR 28827
* elf64-ppc.c (struct ppc_link_hash_table): Add stub_changed.
(STUB_SHRINK_ITER): Move earlier in file.
(ppc_size_one_stub): Detect any change in stub_offset. Keep
larger one if past STUB_SHRINK_ITER.
(ppc64_elf_size_stubs): Iterate on stub_changed too.
Re: PR28827, assertion building LLVM 9 on powerpc64le-linux-gnu
The previous patch wasn't quite correct. The size and padding depends
on offset used in the current iteration, and if we're fudging the
offset past STUB_SHRINK_ITER then we'd better use that offset. We
can't have plt_stub_pad using stub_sec->size as the offset.
PR 28827
* elf64-ppc.c (plt_stub_pad): Add stub_off param.
(ppc_size_one_stub): Set up stub_offset to value used in this
iteration before sizing the stub. Adjust plt_stub_pad calls.
Re: PR28827, assertion building LLVM 9 on powerpc64le-linux-gnu
In trying to find a testcase for PR28827, I managed to hit a linker
error in bfd_set_section_contents with a .branch_lt input section
being too large for the output .branch_lt.
bfd/
PR 28827
* elf64-ppc.c (ppc64_elf_size_stubs): Set section size to
maxsize past STUB_SHRINK_ITER before laying out. Remove now
unnecessary conditional setting of maxsize at start of loop.
ld/
* testsuite/ld-powerpc/pr28827-2.d,
* testsuite/ld-powerpc/pr28827-2.lnk,
* testsuite/ld-powerpc/pr28827-2.s: New test.
* testsuite/ld-powerpc/powerpc.exp: Run it.
Alan Modra [Wed, 19 Jan 2022 13:17:41 +0000 (23:47 +1030)]
Update PowerPC64 symtocbase test
Using a symbol other than .TOC. with @tocbase is an extension to the
ABI. It is never valid to use a symbol without a definition in the
binary, and symbols on these expressions cannot be overridden. Make
this explicit by using ".hidden" in the testcase.
* testsuite/ld-powerpc/symtocbase-1.s: Align data. Make function
entry symbol hidden.
* testsuite/ld-powerpc/symtocbase-2.s: Likewise.
* testsuite/ld-powerpc/symtocbase.d: Adjust expected output.
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