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On platforms that have getrlimit(RLIMIT_STACK), use it to ensure that

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max_stack_depth is not set to an unsafe value.

This commit also provides configure-time checking for <sys/resource.h>,
and cleans up some perhaps-unportable code associated with use of that
include file and getrlimit().
This commit is contained in:
Tom Lane
2006-10-07 19:25:29 +00:00
parent 1c160291ef
commit 71a6f8b85b
9 changed files with 136 additions and 52 deletions
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71
src/backend/tcop/postgres.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.511 2006/10/07 16:43:28 tgl Exp $
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.512 2006/10/07 19:25:28 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@ -23,13 +23,20 @@
#include <signal.h>
#include <fcntl.h>
#include <sys/socket.h>
#if HAVE_SYS_SELECT_H
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#endif
#ifndef HAVE_GETRUSAGE
#include "rusagestub.h"
#endif
#include "access/printtup.h"
#include "access/xact.h"
#include "catalog/pg_type.h"
@ -78,7 +85,7 @@ bool Log_disconnections = false;
LogStmtLevel log_statement = LOGSTMT_NONE;
/* GUC variable for maximum stack depth (measured in kilobytes) */
int max_stack_depth = 2048;
int max_stack_depth = 100;
/* wait N seconds to allow attach from a debugger */
int PostAuthDelay = 0;
@ -91,7 +98,7 @@ int PostAuthDelay = 0;
*/
/* max_stack_depth converted to bytes for speed of checking */
static long max_stack_depth_bytes = 2048 * 1024L;
static long max_stack_depth_bytes = 100 * 1024L;
/*
* Stack base pointer -- initialized by PostgresMain. This is not static
@ -2490,9 +2497,7 @@ ProcessInterrupts(void)
* This should be called someplace in any recursive routine that might possibly
* recurse deep enough to overflow the stack. Most Unixen treat stack
* overflow as an unrecoverable SIGSEGV, so we want to error out ourselves
* before hitting the hardware limit. Unfortunately we have no direct way
* to detect the hardware limit, so we have to rely on the admin to set a
* GUC variable for it ...
* before hitting the hardware limit.
*/
void
check_stack_depth(void)
@ -2530,13 +2535,24 @@ check_stack_depth(void)
}
}
/* GUC assign hook to update max_stack_depth_bytes from max_stack_depth */
/* GUC assign hook for max_stack_depth */
bool
assign_max_stack_depth(int newval, bool doit, GucSource source)
{
/* Range check was already handled by guc.c */
long newval_bytes = newval * 1024L;
long stack_rlimit = get_stack_depth_rlimit();
if (stack_rlimit > 0 && newval_bytes > stack_rlimit - STACK_DEPTH_SLOP)
{
ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("\"max_stack_depth\" must not exceed %ldkB",
(stack_rlimit - STACK_DEPTH_SLOP) / 1024L),
errhint("Increase the platform's stack depth limit via \"ulimit -s\" or local equivalent.")));
return false;
}
if (doit)
max_stack_depth_bytes = newval * 1024L;
max_stack_depth_bytes = newval_bytes;
return true;
}
@ -3635,11 +3651,36 @@ PostgresMain(int argc, char *argv[], const char *username)
return 1; /* keep compiler quiet */
}
#ifndef HAVE_GETRUSAGE
#include "rusagestub.h"
#else
#include <sys/resource.h>
#endif /* HAVE_GETRUSAGE */
/*
* Obtain platform stack depth limit (in bytes)
*
* Return -1 if unlimited or not known
*/
long
get_stack_depth_rlimit(void)
{
#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_STACK)
static long val = 0;
/* This won't change after process launch, so check just once */
if (val == 0)
{
struct rlimit rlim;
if (getrlimit(RLIMIT_STACK, &rlim) < 0)
val = -1;
else if (rlim.rlim_cur == RLIM_INFINITY)
val = -1;
else
val = rlim.rlim_cur;
}
return val;
#else /* no getrlimit */
return -1;
#endif
}
static struct rusage Save_r;
static struct timeval Save_t;