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bug#21004: 25.0.50; Questionable call to getrlimit in handle_sigsegv
From: |
Ken Brown |
Subject: |
bug#21004: 25.0.50; Questionable call to getrlimit in handle_sigsegv |
Date: |
Tue, 07 Jul 2015 16:11:53 -0400 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
There is a call to setrlimit in main() that tries to increase the stack
size. As a result of this, the value of rlim.rlim_cur in
handle_sigsegv() might exceed the actual stack size. See Corinna
Vinschen's message at
https://www.cygwin.com/ml/cygwin/2015-07/msg00092.html
for a more detailed explanation.
Corinna suggests using pthread_getattr_np instead of getrlimit to avoid
this problem, as in the following patch:
diff --git a/src/sysdep.c b/src/sysdep.c
index 91036f0..c49e333 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -1625,6 +1625,8 @@ handle_arith_signal (int sig)
#ifdef HAVE_STACK_OVERFLOW_HANDLING
+#include <pthread.h>
+
/* -1 if stack grows down as expected on most OS/ABI variants, 1
otherwise. */
static int stack_direction;
@@ -1642,9 +1644,11 @@ handle_sigsegv (int sig, siginfo_t *siginfo, void
*arg)
too nested calls to mark_object. No way to survive. */
if (!gc_in_progress)
{
- struct rlimit rlim;
+ pthread_attr_t attr;
+ size_t stacksize;
- if (!getrlimit (RLIMIT_STACK, &rlim))
+ if (!pthread_getattr_np (pthread_self (), &attr)
+ && !pthread_attr_getstacksize (&attr, &stacksize))
{
/* STACK_DANGER_ZONE has to be bigger than 16K on Cygwin, for
reasons explained in
@@ -1657,7 +1661,7 @@ handle_sigsegv (int sig, siginfo_t *siginfo, void
*arg)
char *beg, *end, *addr;
beg = stack_bottom;
- end = stack_bottom + stack_direction * rlim.rlim_cur;
+ end = stack_bottom + stack_direction * stacksize;
if (beg > end)
addr = beg, beg = end, end = addr;
addr = (char *) siginfo->si_addr;
Of course, the definition of HAVE_STACK_OVERFLOW_HANDLING would have to
be changed to ensure that pthread_getattr_np exists.
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- bug#21004: 25.0.50; Questionable call to getrlimit in handle_sigsegv,
Ken Brown <=