Valgrind shows:
==26964== Invalid read of size 1
==26964== at 0x6E14100: __GI_strcmp (strcmp.S:180)
==26964== by 0x6DB55AA: setlocale (setlocale.c:238)
==26964== by 0x4E0455: _initialize_python() (python.c:1731)
==26964== by 0x786731: initialize_all_files() (init.c:319)
==26964== by 0x72EF0A: gdb_init(char*) (top.c:1929)
==26964== by 0x60BCAC: captured_main(void*) (main.c:863)
==26964== by 0x606AD5: catch_errors(int (*)(void*), void*, char*, return_mask) (exceptions.c:234)
==26964== by 0x60C608: gdb_main(captured_main_args*) (main.c:1165)
==26964== by 0x40CAEC: main (gdb.c:32)
==26964== Address 0x81d30a0 is 0 bytes inside a block of size 181 free'd
==26964== at 0x4C29CF0: free (vg_replace_malloc.c:530)
==26964== by 0x6DB5B65: setname (setlocale.c:201)
==26964== by 0x6DB5B65: setlocale (setlocale.c:388)
==26964== by 0x4E037F: _initialize_python() (python.c:1712)
==26964== by 0x786731: initialize_all_files() (init.c:319)
==26964== by 0x72EF0A: gdb_init(char*) (top.c:1929)
==26964== by 0x60BCAC: captured_main(void*) (main.c:863)
==26964== by 0x606AD5: catch_errors(int (*)(void*), void*, char*, return_mask) (exceptions.c:234)
==26964== by 0x60C608: gdb_main(captured_main_args*) (main.c:1165)
==26964== by 0x40CAEC: main (gdb.c:32)
The problem is doing this:
oldloc = setlocale (LC_ALL, NULL);
setlocale (LC_ALL, "");
...
setlocale (LC_ALL, oldloc);
I.e., the second setlocale call frees 'oldloc'.
From http://pubs.opengroup.org/onlinepubs/9699919799/functions/setlocale.html :
"The returned string pointer might be invalidated or the string
content might be overwritten by a subsequent call to setlocale()."
gdb/ChangeLog:
2016-05-03 Pedro Alves <palves@redhat.com>
PR python/20037
* python/python.c (_initialize_python) [IS_PY3K]: xstrdup/xfree
oldloc.
This makes no sense -- strlen doesn't really ever fail with -1.
gdb/ChangeLog:
2016-05-03 Pedro Alves <palves@redhat.com>
* python/python.c (_initialize_python) [IS_PY3K]: Remove dead
code.
When handling absolute relocations for global symbols bind within the
shared object, AArch64 will generate one dynamic RELATIVE relocation,
but won't apply the value for this absolution relocations at static
linking stage. This is different from AArch64 gold linker and x86-64.
This is not a bug as AArch64 is RELA, there is only guarantee that
relocation addend is placed in the relocation entry. But some
system softwares originally writen for x86-64 might assume AArch64
bfd linker gets the same behavior as x86-64, then they could take
advantage of this buy skipping those RELATIVE dynamic relocations
if the load address is the same as the static linking address.
This patch makes AArch64 BFD linker applies absolution relocations at
static linking stage for scenario described above. Meanwhile old AArch64
android loader has a bug (PR19163) which relies on current linker behavior
as a workaround, so the same option --no-apply-dynamic-relocs added.
GDB's use of --dynamic-list to only export the proc-service symbols is
broken due to Python's "python-config --ldflags" saying we should link
with -export-dynamic, causing us to export _all_ extern symbols
anyway. On Fedora 23:
$ python-config --ldflags
-lpython2.7 -lpthread -ldl -lutil -lm -Xlinker -export-dynamic
$ python3.4-config --ldflags
-L/usr/lib64 -lpython3.4m -lpthread -ldl -lutil -lm -Xlinker -export-dynamic
Having GDB export all its symbols leads to issues such as PR gdb/16818
(GDB crashes when using name for target remote hostname:port), where a
GDB symbol unintentionally preempts a symbol in one of the NSS modules
glibc loads into the process. NSS modules should not define symbols
outside the implementation namespace or the relevant standards, but,
alas, that's a longstanding and hard to fix issue. See libc-alpha
discussion at:
[symbol name space issues with NSS modules]
https://sourceware.org/ml/libc-alpha/2016-04/msg00130.html
Python should instead be either using GCC's symbol visibility feature
or -Wl,--dynamic-list as well, to only export Python API symbols, but,
it doesn't. There are bugs open upstream for that:
[Use -Wl,--dynamic-list=x.list, not -Xlinker -export-dynamic]
http://bugs.python.org/issue10112
[Use GCC visibility attrs in PyAPI_*]
http://bugs.python.org/issue11410
But that's taking a long while to resolve.
I thought of working around this Python issue by making GDB build with
-fvisibility=hidden, as Jan suggests in Python issue 10112, as then
Python's "-Xlinker -export-dynamic" has no effect. However, that
would need to be done in the whole source tree (bfd, libiberty, etc.),
and I think that would break GCC plugins, as I believe those have
access to all of GCCs symbols, by "design". So we'd need a new
configure switch, or have the libraries in the tree detect which of
GCC or GDB is being built, but that doesn't work, because the answer
can be "both" with combined builds...
So this patch instead works around Python's bug, by simply sed'ing
away "-Xlinker -export-dynamic" from the result of python-config.py
--ldflags, making -Wl,--dynamic-list work again as it used to. It's
ugly, but so is the bug...
Note that if -Wl,--dynamic-list doesn't work, we always link with
-rdynamic, so static Python should still work.
Tested on F23 with --python=python (Python 2.7) and
--python=python3.4.
gdb/ChangeLog:y
2016-05-03 Pedro Alves <palves@redhat.com>
* configure.ac (PYTHON_LIBS): Sed away "-Xlinker -export-dynamic".
* configure: Regenerate.
The -Wl,--dynamic-list test is currently broken on Fedora 23, when you
configure with --with-python=python3.4. We see:
configure:13741: checking for the dynamic export flag
configure:13796: gcc -o conftest -g3 -O0 -fno-strict-aliasing -DNDEBUG -fwrapv -Wl,--dynamic-list=/home/pedro/gdb/mygit/src/gdb/proc-service.list conftest.c -ldl -lncurses -lm -ldl -lpthread -ldl -lutil -lm -lpython3.4m -Xlinker -export-dynamic >&5
conftest.c:182:30: fatal error: python3.4/Python.h: No such file or directory
compilation terminated.
configure:13796: $? = 1
The correct -I path is in PYTHON_CPPFLAGS:
PYTHON_CPPFLAGS='-I/usr/include/python3.4m -I/usr/include/python3.4m'
(Other Python-related tests in the file are already doing this.)
gdb/ChangeLog:
2016-05-03 Pedro Alves <palves@redhat.com>
* configure.ac (checking for the dynamic export flag): Add
$PYTHON_CPPFLAGS to CPPFLAGS.
* configure: Regenerate.
This test seems to work with both native-gdbserver and
native-extended-gdbserver, so I removed the remote check.
When running with native-gdbserver (a stub-like target), detach makes
gdbserver stop and gdb disconnect. runto_main just spawns a brand new
gdbserver. So it tests the exact same thing twice. It doesn't hurt
though.
With native-extended-gdbserver, the test is probably a bit more useful
(and similar to native). It tests running/detaching twice using the
same gdb/gdbserver instances, since with extended-remote, you can
detach/attach/run all you want, unlike with remote.
gdb/testsuite/ChangeLog:
* gdb.base/detach.exp: Remove is_remote check.
The comment says that we can't use runto_main here becore it doesn't
know how to handle annotation. Instead, the test puts a breakpoint at
main and calls run by hand. Therefore, it can't work with stub targets,
since they can't "run". The check should be then changed to check the
use_gdb_stub variable instead of [is_remote target].
But as an alternative, we can just use runto_main and enable annotations
after, since the "run to main" part is not really part of what we want
to test.
I also removed the "set test..." line that is unused.
gdb/testsuite/ChangeLog:
* gdb.base/annota-input-while-running.exp: Don't check for
[is_remote target]. Enable annotations after running to main.
Remove unused "set test..." line.
* windows-nat.c (_initialize_check_for_gdb_ini): Fix off-by-one
error in allocation of space for "$HOME/.gdbinit" string. This
caused GDB to abort on startup whenever a '~/gdb.ini' file was
actually found, because xsnprintf would hit an assertion
violation.
Set interpreter in x86 create_dynamic_sections to make this information
available to x86 check_relocs.
* elf32-i386.c (elf_i386_size_dynamic_sections): Move interp
setting to ...
(elf_i386_create_dynamic_sections): Here.
* elf64-x86-64.c (elf_x86_64_size_dynamic_sections): Move
interp setting to ...
(elf_x86_64_create_dynamic_sections): Here.
When UNDEFINED_WEAK_RESOLVED_TO_ZERO is checked to convert load via
GOT, has_got_reloc is always TRUE. This patch adds GOT_RELOC, which
is TRUE in x86 convert_load, to UNDEFINED_WEAK_RESOLVED_TO_ZERO.
* elf32-i386.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): Take GOT_RELOC
and replace (EH)->has_got_reloc with GOT_RELOC.
(elf_i386_fixup_symbol): Pass has_got_reloc to
UNDEFINED_WEAK_RESOLVED_TO_ZERO.
(elf_i386_allocate_dynrelocs): Likewise.
(elf_i386_relocate_section): Likewise.
(elf_i386_finish_dynamic_symbol): Likewise.
(elf_i386_convert_load): Pass TRUE to
UNDEFINED_WEAK_RESOLVED_TO_ZERO.
* elf64-x86-64.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): Take
GOT_RELOC and replace (EH)->has_got_reloc with GOT_RELOC.
(elf_x86_64_fixup_symbol): Pass has_got_reloc to
UNDEFINED_WEAK_RESOLVED_TO_ZERO.
(elf_x86_64_allocate_dynrelocs): Likewise.
(elf_x86_64_relocate_section): Likewise.
(elf_x86_64_finish_dynamic_symbol): Likewise.
(elf_x86_64_convert_load): Pass TRUE to
UNDEFINED_WEAK_RESOLVED_TO_ZERO.
There is no need to download source if we aren't on remote host.
Otherwise, each ld test run on local host leaves behind a couple
test files.
* config/default.exp (NOPIE_CFLAGS): Download source only on
remote host.
(NOPIE_LDFLAGS): Likewise.
* testsuite/lib/ld-lib.exp (check_lto_available): Likewise.
(check_lto_fat_available): Likewise.
(check_lto_shared_available): Likewise.
(check_ifunc_available): Likewise.
(check_ifunc_attribute_available): Likewise.
* readelf.c (is_32bit_pcrel_reloc): Return true if reloc is 32-bit
PC relocation for AVR target.
(is_none_reloc): Return true if reloc is any of AVR diff
relocations.
No need to relocate section when check_relocs failed.
* elf32-i386.c (check_relocs_failed): New.
(elf_i386_check_relocs): Set check_relocs_failed on error.
(elf_i386_relocate_section): Skip if check_relocs failed.
PR 19938
bfd * elf-bfd.h (struct elf_backend_data): Rename
elf_backend_set_special_section_info_and_link to
elf_backend_copy_special_section_fields.
* elfxx-target.h: Likewise.
* elf.c (section_match): Ignore the SHF_INFO_LINK flag when
comparing section flags.
(copy_special_section_fields): New function.
(_bfd_elf_copy_private_bfd_data): Copy the EI_ABIVERSION field.
Perform two scans over special sections. The first one looks for
a direct mapping between the output section and an input section.
The second scan looks for a possible match based upon section
characteristics.
* elf32-arm.c (elf32_arm_copy_special_section_fields): New
function. Handle setting the sh_link field of SHT_ARM_EXIDX
sections.
* elf32-i386.c (elf32_i386_set_special_info_link): Rename to
elf32_i386_copy_solaris_special_section_fields.
* elf32-sparc.c (elf32_sparc_set_special_section_info_link):
Rename to elf32_sparc_copy_solaris_special_section_fields.
* elf64-x86-64.c (elf64_x86_64_set_special_info_link): Rename to
elf64_x86_64_copy_solaris_special_section_fields.
binutils* readelf.c (get_solaris_segment_type): New function.
(get_segment_type): Call it.
Just like completion doesn't show deprecated commands, I think that help
should not list them, so that we don't incite users to use them.
gdb/ChangeLog:
* cli/cli-decode.c (help_cmd_list): Do not list commands that
are deprecated.
This patch adds a test for tracepoints enabling/disabling, which
didn't work properly for fast tracepoints on big endian systems.
gdb/testsuite/ChangeLog:
* gdb.trace/trace-enable-disable.exp: New file.
* gdb.trace/trace-enable-disable.c: New file.
I am sending this fix on behalf of Par Olsson, as a follow-up of this
one:
https://www.sourceware.org/ml/gdb-patches/2015-10/msg00196.html
This problem is exposed when enabling/disabling fast tracepoints on big
endian machines. The flag is defined as an int8_t, but is written from
gdbserver as an integer (usually 32 bits). When the agent code reads it
as an int8_t, it only considers the most significant byte, which is
always 0.
Also, we were writing 32 bits in an 8 bits field, so the write would
overflow, but since the following bytes are padding (the next field is
an uint64_t), it luckily didn't cause any issue on little endian
systems.
The fix was originally tested on ARM big endian systems, but I don't
have access to such a system. However, thanks to Marcin's PowerPC fast
tracepoint patches and gcc110 (big endian Power7) on the gcc compile
farm, I was able to reproduce the problem, test the fix and write a
test (the following patch).
gdb/gdbserver/ChangeLog:
YYYY-MM-DD Par Olsson <par.olsson@windriver.com>
* tracepoint.c (write_inferior_int8): New function.
(cmd_qtenable_disable): Write enable flag using
write_inferior_int8.
Some fast tracepoints tests make sure that the in-process agent library
is properly loaded, by searching for the library name in "info
sharedlibrary".
Originally, it would search for the full path. Since patch "Make ftrace
tests work with remote targets" [1], the "runtime" location of the IPA,
in the standard output directory, is not the same as the original
location, in the gdbserver build directory. Therefore, the patch
changed the checks:
gdb_test "info sharedlibrary" ".*${libipa}.*" "IPA loaded"
to
gdb_test "info sharedlibrary" ".*[file tail ${libipa}].*" "IPA loaded"
so that only the "libinproctrace.so" part would be searched for.
Antoine (in CC) pointed out that I missed some, so I have to update
them. In the mean time, I noticed that I missed a few test failures:
adding the SONAME to the IPA makes it possible for the test executable
to erroneously pick up libinproctrace.so from /usr/lib if the test
harness failed to put the libinproctrace.so we want to test in the right
place. To mitigate that kind of error in the future, we can use the
return value of gdb_load_shlib (the path of the "runtime" version of the
library) and use that to search in the output of info sharedlibrary.
When testing locally, gdb_load_shlib returns the full normalized path of
the destination library, which the test executable should use e.g.:
/path/to/gdb/testsuite/outputs/gdb.trace/thetest/libinproctrace.so
My testing showed that it was the same path that gdb displayed in info
sharedlibrary. If the test executable picks up another
libinproctrace.so, the test will fail.
When testing remotely, gdb_load_shlib/gdb_remote_download only returns
us "libinproctrace.so", so the situation doesn't really change. If
there is a rogue libinproctrace.so in /usr/lib on the target and we fail
to download ours, it might cover up a test failure. But that situation
is probably still better than the original one, where it wasn't possible
to test remotely using the IPA at all.
[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=6e774b13c3b81ac2599812adf058796948ce7e95
gdb/testsuite/ChangeLog:
* gdb.arch/ftrace-insn-reloc.exp: Save gdb_load_shlib result,
use it in info sharedlibrary test.
* gdb.trace/ftrace-lock.exp: Likewise.
* gdb.trace/ftrace.exp: Likewise.
* gdb.trace/range-stepping.exp: Likewise.
* gdb.trace/trace-break.exp: Likewise.
* gdb.trace/trace-condition.exp: Likewise.
* gdb.trace/trace-mt.exp: Likewise.
Hi,
I happen to see that field need_step_over in struct lwp_info is only
used to print a debug info. need_step_over is set in linux_wait_1
when breakpoint_here is true, however, we check breakpoint_here too in
need_step_over_p and do the step over. I think we don't need field
need_step_over, and check breakpoint_here directly in need_step_over_p.
This field was added in this patch
https://sourceware.org/ml/gdb-patches/2010-03/msg00605.html and the code
wasn't changed much since then.
This patch is to remove it.
gdb/gdbserver:
2016-04-28 Yao Qi <yao.qi@linaro.org>
* linux-low.h (struct lwp_info) <need_step_over>: Remove.
* linux-low.c (linux_wait_1): Update.
(need_step_over_p): Likewise.
PR target/19722
opcodes * aarch64-dis.c (aarch64_opcode_decode): Run verifier if present.
* aarch64-opc.c (verify_ldpsw): New function.
* aarch64-opc.h (verify_ldpsw): New prototype.
* aarch64-tbl.h: Add initialiser for verifier field.
(LDPSW): Set verifier to verify_ldpsw.
binutils* testsuite/binutils-all/aarch64/illegal.s: New test.
* testsuite/binutils-all/aarch64/illegal.d: New test driver.
include * opcode/aarch64.h (struct aarch64_opcode): Add verifier field.
Since not all ELF targets use the elf.em emulation to support ld option:
--compress-debug-sections=zlib-gnu, limit compressed1b.d to Linux/GNU
targets.
* testsuite/ld-elf/compressed1b.d: Only run for Linux/GNU targets.
This patch makes gdb_load_shlibs return the destination path of the
copied library. To make the procedure implementation and interface more
straightforward, it also changes it so that it accepts a single shared
library path at the time. Therefore, calls that are passed multiple
libraries:
gdb_load_shlibs $lib1 $lib2
must be changed to separate calls:
gdb_load_shlibs $lib1
gdb_load_shlibs $lib2
A subtle impact is the solib-search-path handling. In the former
version, solib-search-path is set using the directory of the first
passed lib (further calls overwrite the value). In the later version,
the directory of the library passed to the last call to gdb_load_shlibs
remnains. I don't think that's a problem in practice, since if we had
tests that needed multiple different paths in solib-search-path, they
wouldn't work in the first place.
Changed in v2:
* Split behavioural and rename changes in two separate patches.
gdb/testsuite/ChangeLog:
* lib/gdb.exp (gdb_load_shlibs): Accept a single argument. Return
result of gdb_remote_download.
* gdb.base/ctxobj.exp: Split gdb_load_shlibs call.
* gdb.base/dso2dso.exp: Likewise.
* gdb.base/global-var-nested-by-dso.exp: Likewise.
* gdb.base/print-file-var.exp: Likewise.
* gdb.base/shlib-call.exp: Likewise.
* gdb.base/shreloc.exp: Likewise.
* gdb.base/solib-overlap.exp: Likewise.
* gdb.base/solib-weak.exp (do_test): Likewise.
* gdb.base/unload.exp: Likewise.
With current FSF GDB HEAD and old FSF gdbserver I expected I could do:
gdb -ex 'file target:/root/redhat/threadit' -ex 'target remote :1234'
(supplying that unsupported qXfer:exec-file:read by "file")
But that does not work because:
Sending packet: $vFile:setfs:0#bf...Packet received: OK
Packet vFile:setfs (hostio-setfs) is supported
...
Sending packet: $vFile:setfs:104#24...Packet received: OK
"target:/root/redhat/threadit": could not open as an executable file: Invalid argument
GDB documentation says:
The valid responses to Host I/O packets are:
An empty response indicates that this operation is not recognized.
This "empty response" vs. "OK" was a bug in gdbserver < 7.7. It was fixed by:
commit e7f0d979dd
Author: Yao Qi <yao@codesourcery.com>
Date: Tue Dec 10 21:59:20 2013 +0800
Fix a bug in matching notifications.
Message-ID: <1386684626-11415-1-git-send-email-yao@codesourcery.com>
https://sourceware.org/ml/gdb-patches/2013-12/msg00373.html
2013-12-10 Yao Qi <yao@codesourcery.com>
* notif.c (handle_notif_ack): Return 0 if no notification
matches.
with unpatched old FSF gdbserver and patched FSF GDB HEAD:
gdb -ex 'file target:/root/redhat/threadit' -ex 'target remote :1234'
Sending packet: $vFile:setfs:0#bf...Packet received: OK
Packet vFile:setfs (hostio-setfs) is NOT supported
...
(gdb) info sharedlibrary
From To Syms Read Shared Object Library
0x00007ffff7ddbae0 0x00007ffff7df627a Yes (*) target:/lib64/ld-linux-x86-64.so.2
0x00007ffff7bc48a0 0x00007ffff7bcf514 Yes (*) target:/lib64/libpthread.so.0
gdb/ChangeLog
2016-04-26 Jan Kratochvil <jan.kratochvil@redhat.com>
* remote.c (remote_start_remote): Detect PACKET_vFile_setfs.support.
Skip debug sections when estimating distances between output sections
since compressed_size is used to compress debug sections and debug
sections aren't excluded from distances between output sections.
bfd/
PR ld/20006
* elf64-x86-64.c (elf_x86_64_convert_load): Skip debug sections
when estimating distances between output sections.
ld/
PR ld/20006
* testsuite/ld-elfvsb/elfvsb.exp (COMPRESS_LDFLAG): New.
(visibility_run): Pass COMPRESS_LDFLAG to visibility_test on
ELF targets.
I get a timeout fail in branch-to-self.exp when it is compiled by a
bare-mental target running qemu, which doesn't have signal.
The test should be skipped if gdb,nosignals exists, and that is
what this patch does.
gdb/testsuite:
2016-04-27 Yao Qi <yao.qi@linaro.org>
* gdb.base/branch-to-self.exp: Skip it if gdb,nosignals
exists.
Currently c_value_print will turn struct reference values into pointers before
doing a set of RTTI checks. This was introduced as a fix to PR c++/15401.
If there's RTTI the pointer will be adjusted and converted back to a reference.
However, if there's no RTTI the value will still be treated as a pointer during
the remainder of the function.
This patch moves the conversion down so that it's always performed when needed.
Notice this currently has not user-visible effects, so can be seen as a small
code cleanup. However, it'll be necessary for the bug-fix for handling
synthetic C++ references. It causes no testsuite regressions.
gdb/ChangeLog:
2016-04-26 Martin Galvan <martin.galvan@tallertechnologies.com>
* c-valprint.c (c_value_print): Always convert val back to reference
type if we converted it to a pointer type.
Hi,
command "tfind" will find the first trace snapshot if no trace
snapshot is selected, but this behavior isn't documented.
This patch completes the doc of command "tfind" without argument.
gdb/doc:
2016-04-27 Yao Qi <yao.qi@linaro.org>
* gdb.texinfo (tfind): Complete doc about tfind without
argument.
In some babeltrace versions before 1.2.0, the header file iterator.h
declares the enum values `BT_SEEK_*' within the struct declaration of
bt_iter_pos. The enum values are supposed to be globally-scoped, which
works for C, but not for C++. Later babeltrace versions declare the
enum outside the struct:
https://lists.lttng.org/pipermail/lttng-dev/2013-September/021411.html
Now that GDB is compiled with C++, the GDB build fails on a system with
an affected babeltrace version: the compiler complains about a missing
declaration of BT_SEEK_BEGIN in ctf.c.
This patch enhances the configure check to recognize such babeltrace
versions as unusable for GDB.
gdb/ChangeLog:
* configure.ac: Enhance configure check for babeltrace to reject
non-C++-enabled versions.
* configure: Regenerate.
Since ld may generate compressed debug sections by default, pass
--compress-debug-sections=none to ld to avoid compressed debug
sections.
* ld-elf/compressed1b.d: Pass --compress-debug-sections=none
to ld.
* ld-elf/compressed1c.d: Likewise.
include/
* bfdlink.h (struct bfd_link_hash_entry): Add "section" field to
undef. Formatting.
bfd/
* elflink.c (_bfd_elf_is_start_stop): New function.
(_bfd_elf_gc_mark_rsec): Use it.
* elf-bfd.h (_bfd_elf_is_start_stop): Declare.
arithmetic on void * is undefined in ISO C, so we should avoid it. In
GNU C sizeof void * is defined as 1, and that is pretty clearly what
this code wants, so change it to do arithmetic on bfd_byte *.
Unfortunately most of the argument types come from virtual function
interfaces so changing the types to bfd_byte * isn't trivial though it
might make the code clearer. So for the moment its easiest to leave the
variable types as void * and cast before doing arithmetic.
bfd/ChangeLog:
2016-04-26 Trevor Saunders <tbsaunde+binutils@tbsaunde.org>
* elf32-rx.c (rx_set_section_contents): Avoid arithmetic on void *.
* mmo.c (mmo_get_section_contents): Likewise.
(mmo_set_section_contents): Likewise.
