Hello list!
The 0x20000 crash the subject refers to is a crash which is special in
that it is caused by attempting to access memory at address 0x20000
which is unallocated resulting in a segmentation fault.
The error is triggered when hostname resolution via DNS fails (I am
using gethostbyname() ).
I think this was discussed long time ago in some bug filing that I saw
a few years ago, that it was understood the error is specific to the
x86_64 architecture and that the cause was not known at the time.
However, the error was partially fixed sometime after that - as I saw in
the git repository just now.
The problem is that va_lists are handled in a brittle way by x86_64 and
need to be copied whenever even a small breeze blows. More info:
http://www.bailopan.net/blog/?p=30
The patch is against Polipo-1.0.4.1, before the fix in the repository
was made. Beside the fix already in the repository, the patch also
va_copies the va_list arguments whenever they are passed through a
function. It also calls va_end after all instances of va_copy (the code
in repository does not).
--
Fourth law of programming:
Anything that can go wrong wi
sendmail: segmentation violation - core dumped
diff -Naur polipo-1.0.4.1-old/log.c polipo-1.0.4.1-new/log.c
--- polipo-1.0.4.1-old/log.c 2010-02-01 00:13:20.000000000 +0100
+++ polipo-1.0.4.1-new/log.c 2012-07-03 20:58:25.000000000 +0200
@@ -279,11 +279,14 @@
accumulateSyslogV(int type, const char *f, va_list args)
{
int rc;
+ va_list args2;
again:
+ va_copy(args2, args);
rc = vsnprintf(syslogBuf + syslogBufLength,
syslogBufSize - syslogBufLength,
- f, args);
+ f, args2);
+ va_end(args2);
if(rc < 0 || rc >= syslogBufSize - syslogBufLength) {
rc = expandSyslog(rc);
@@ -370,12 +373,20 @@
void
really_do_log_v(int type, const char *f, va_list args)
{
+ va_list args2, args3;
+
if(type & LOGGING_MAX & logLevel) {
- if(logF)
- vfprintf(logF, f, args);
+ if(logF) {
+ va_copy(args2, args);
+ vfprintf(logF, f, args2);
+ va_end(args2);
+ }
#ifdef HAVE_SYSLOG
- if(logSyslog)
- accumulateSyslogV(type, f, args);
+ if(logSyslog) {
+ va_copy(args3, args);
+ accumulateSyslogV(type, f, args3);
+ va_end(args3);
+ }
#endif
}
}
@@ -393,13 +404,17 @@
void
really_do_log_error_v(int type, int e, const char *f, va_list args)
{
+ va_list args2, args3;
+
if((type & LOGGING_MAX & logLevel) != 0) {
char *es = pstrerror(e);
if(es == NULL)
es = "Unknown error";
if(logF) {
- vfprintf(logF, f, args);
+ va_copy(args2, args);
+ vfprintf(logF, f, args2);
+ va_end(args2);
fprintf(logF, ": %s\n", es);
}
#ifdef HAVE_SYSLOG
@@ -407,7 +422,9 @@
char msg[256];
size_t n = 0;
- n = snnvprintf(msg, n, 256, f, args);
+ va_copy(args3, args);
+ n = snnvprintf(msg, n, 256, f, args3);
+ va_end(args3);
n = snnprintf(msg, n, 256, ": ");
n = snnprint_n(msg, n, 256, es, strlen (es));
n = snnprintf(msg, n, 256, "\n");
diff -Naur polipo-1.0.4.1-old/util.c polipo-1.0.4.1-new/util.c
--- polipo-1.0.4.1-old/util.c 2010-02-01 00:13:20.000000000 +0100
+++ polipo-1.0.4.1-new/util.c 2012-07-03 20:53:30.000000000 +0200
@@ -50,9 +50,12 @@
snnvprintf(char *restrict buf, int n, int len, const char *format, va_list args)
{
int rc = -1;
+ va_list args2;
if(n < 0) return -2;
if(n < len)
- rc = vsnprintf(buf + n, len - n, format, args);
+ va_copy(args2, args);
+ rc = vsnprintf(buf + n, len - n, format, args2);
+ va_end(args2);
if(rc >= 0 && n + rc <= len)
return n + rc;
else
@@ -268,7 +271,10 @@
{
char *r;
int rc;
- rc = vasprintf(&r, f, args);
+ va_list args2;
+ va_copy(args2, args);
+ rc = vasprintf(&r, f, args2);
+ va_end(args2);
if(rc < 0)
return NULL;
return r;
@@ -281,9 +287,14 @@
int n, size;
char buf[64];
char *string;
+ va_list args2, args3, args4;
- n = vsnprintf(buf, 64, f, args);
+ va_copy(args2, args);
+ va_copy(args4, args);
+ n = vsnprintf(buf, 64, f, args4);
+ va_end(args4);
if(n >= 0 && n < 64) {
+ va_end(args2);
return strdup_n(buf, n);
}
if(n >= 64)
@@ -293,18 +304,25 @@
while(1) {
string = malloc(size);
- if(!string)
+ if(!string) {
+ va_end(args2);
return NULL;
- n = vsnprintf(string, size, f, args);
- if(n >= 0 && n < size)
+ }
+ va_copy(args3, args2);
+ n = vsnprintf(string, size, f, args3);
+ va_end(args3);
+ if(n >= 0 && n < size) {
+ va_end(args2);
return string;
- else if(n >= size)
+ } else if(n >= size)
size = n + 1;
else
size = size * 3 / 2;
free(string);
- if(size > 16 * 1024)
+ if(size > 16 * 1024) {
+ va_end(args2);
return NULL;
+ }
}
/* NOTREACHED */
}
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