83c39aedac
As described in nano-mallocr.c, chunks of heap are represented in memory as a size (of type long), followed by some optional padding containing a negative offset to size, followed by the data area. get_chunk_from_ptr is responsible for taking a pointer to the data area (as returned by malloc) and finding the start of the chunk. It does this by assuming there is no padding and trying to read the size, if the size is negative then it uses that as an offset to find the true size. Crucially, it reads the padding area as a long. nano_malloc is responsible for populating the optional padding area. It does so by casting a pointer to an (int *) and writing the negative offset into it. This means that padding is being written as an int but read as a long. On msp430 an int is 2 bytes, while a long is 4 bytes. This means that 2 bytes are written to the padding, but 4 bytes are read from it: it has only been partially initialised. nano_malloc is the default malloc implementation for msp430. This patch changes the cast from (int *) to (long *). The change to nano_malloc has has been observed to fix a TI Energia project that had been malfunctioning because malloc was returning invalid addresses. The change to nano_memalign is based entirely on code inspection. I've built and tested as follows: Configured (gcc+newlib) with: --target=msp430-elf --enable-languages=c gcc testsuite variations: msp430-sim/-mcpu=msp430 msp430-sim/-mcpu=msp430x msp430-sim/-mcpu=msp430x/-mlarge/-mdata-region=either/-mcode-region=either msp430-sim/-mhwmult=none msp430-sim/-mhwmult=f5series My testing has shown no regressions, however I don't know if the gcc testsuite provides sufficient coverage for this patch? I don't have write access, so if this patch is acceptable after review, I would appreciate it if someone would commit it for me. Thanks, 2017-01-XX Joe Seymour <joe.s@somniumtech.com> newlib/ * libc/stdlib/nano-mallocr.c (nano_malloc): Fix incorrect cast. (nano_memalign): Likewise. |
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README
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.