Commit b74db634 authored by Paul Eggert's avatar Paul Eggert

Backtrace after malloc arena is corrupted

Without this change, if the malloc arena is corrupted and then
'backtrace' is called, the backtrace can crash because 'backtrace'
calls 'malloc'.  For more, please see:
https://sourceware.org/ml/libc-alpha/2015-02/msg00678.html
* emacs.c (main): Initialize tables used by 'backtrace'.
* sysdep.c (emacs_backtrace): Document the newly used part of the API.
parent 0c4f73a0
2015-02-25 Paul Eggert <eggert@cs.ucla.edu>
Backtrace after malloc arena is corrupted
Without this change, if the malloc arena is corrupted and then
'backtrace' is called, the backtrace can crash because 'backtrace'
calls 'malloc'. For more, please see:
https://sourceware.org/ml/libc-alpha/2015-02/msg00678.html
* emacs.c (main): Initialize tables used by 'backtrace'.
* sysdep.c (emacs_backtrace): Document the newly used part of the API.
2015-02-22 Jan Djärv <jan.h.d@swipnet.se>
* nsfns.m (Fx_frame_geometry): New function.
......
......@@ -884,6 +884,8 @@ main (int argc, char **argv)
clearerr (stdin);
emacs_backtrace (-1);
#if !defined SYSTEM_MALLOC && !defined HYBRID_MALLOC
/* Arrange to get warning messages as memory fills up. */
memory_warnings (0, malloc_warning);
......
......@@ -2147,7 +2147,17 @@ snprintf (char *buf, size_t bufsize, char const *format, ...)
/* If a backtrace is available, output the top lines of it to stderr.
Do not output more than BACKTRACE_LIMIT or BACKTRACE_LIMIT_MAX lines.
This function may be called from a signal handler, so it should
not invoke async-unsafe functions like malloc. */
not invoke async-unsafe functions like malloc.
If BACKTRACE_LIMIT is -1, initialize tables that 'backtrace' uses
but do not output anything. This avoids some problems that can
otherwise occur if the malloc arena is corrupted before 'backtrace'
is called, since 'backtrace' may call malloc if the tables are not
initialized.
If the static variable THREAD_BACKTRACE_NPOINTERS is nonzero, a
fatal error has occurred in some other thread; generate a thread
backtrace instead, ignoring BACKTRACE_LIMIT. */
void
emacs_backtrace (int backtrace_limit)
{
......
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