Simon Marchi 9ecab40c77 gdb/arm: avoid undefined behavior shift when decoding immediate value
When loading the code file provided in PR 26828 and GDB is build with
UBSan, we get:

    Core was generated by `./Foo'.
    Program terminated with signal SIGABRT, Aborted.
    #0  0xb6c3809c in pthread_cond_wait () from /home/simark/build/binutils-gdb/gdb/repo/lib/libpthread.so.0
    [Current thread is 1 (LWP 29367)]
    (gdb) bt
    /home/simark/src/binutils-gdb/gdb/arm-tdep.c:1551:30: runtime error: shift exponent 32 is too large for 32-bit type 'unsigned int'

The sequence of instructions at pthread_cond_wait, in the
libpthread.so.0 library, contains this instruction with an immediate
constant with a "rotate amount" of 0:

    e24dd044        sub     sp, sp, #68     ; 0x44

Since arm_analyze_prologue shifts by "32 - rotate amount", it does a 32
bit shift of a 32 bit type, which is caught by UBSan.

Fix it by factoring out the decoding of immediates in a new function,
arm_expand_immediate.

I added a selftest for arm_analyze_prologue that replicates the
instruction sequence.  Without the fix, it crashes GDB if it is build
with --enable-ubsan.

I initially wanted to re-use the abstract_memory_reader class already in
arm-tdep.c, used to make arm_process_record testable.  However,
arm_process_record and arm_analyze_prologue don't use the same kind of
memory reading functions.  arm_process_record uses a function that
returns an error status on failure while arm_analyze_prologue uses one
that throws an exception.  Since i didn't want to introduce any other
behavior change, I decided to just introduce a separate interface
(arm_instruction_reader).  It is derived from
abstract_instruction_reader in aarch64-tdep.c.

gdb/ChangeLog:

	PR gdb/26835
	* arm-tdep.c (class arm_instruction_reader): New.
	(target_arm_instruction_reader): New.
	(arm_analyze_prologue): Add instruction reader parameter and use
	it.  Use arm_expand_immediate.
	(class target_arm_instruction_reader): Adjust.
	(arm_skip_prologue): Adjust.
	(arm_expand_immediate): New.
	(arm_scan_prologue): Adjust.
	(arm_analyze_prologue_test): New.
	(class test_arm_instruction_reader): New.

Change-Id: Ieb1c1799bd66f8c7421384f44f5c2777b578ff8d
2020-11-13 11:58:37 -05:00
2020-11-13 00:00:20 +00:00
2020-09-08 20:12:57 +09:30
2020-09-25 10:24:44 -04:00
2020-10-05 14:20:15 +01:00
2020-02-20 13:02:24 +10:30
2020-11-09 12:05:39 +01:00
2020-10-21 11:52:17 -06:00
2019-12-26 06:54:58 +01:00
2020-02-07 08:42:25 -07:00

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.
Description
Unofficial mirror of sourceware binutils-gdb repository. Updated daily.
Readme 780 MiB
Languages
C 51.8%
Makefile 22.4%
Assembly 12.3%
C++ 6%
Roff 1.4%
Other 5.4%