mariadb/mysys/my_once.c
Nisha Gopalakrishnan 62e8f25677 Bug#11757464:SERVER CRASH IN RECURSIVE CALL WHEN OOM
Analysis:
---------

When the server is out of memory, an error is raised
to indicate the same. Handling the error requires
more memory to be allocated which fails, hence the
error handling loops in a recursion and causes the
server to crash.

Fix:
---
a) Prevents pushing the 'out of memory' error condition
to the diagnostic area as it requires memory allocation.
GET DIAGNOSTICS, SHOW WARNINGS and SHOW ERRORS statements
will not show information about this error. However the
'out of memory' error is returned to the client.
b) It sets the ME_FATALERROR flag when 'out of memory' errors
are reported (for places where the flag is not already set).
This flag prevents activation of SP error handlers which also
require memory allocation and therefore are likely to fail.
2013-01-15 15:30:26 +05:30

119 lines
2.9 KiB
C

/* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
/* Not MT-SAFE */
#include "mysys_priv.h"
#include "my_static.h"
#include "mysys_err.h"
#include <m_string.h>
/*
Alloc for things we don't nend to free run-time (that only
should be free'd on exit)
SYNOPSIS
my_once_alloc()
Size
MyFlags
NOTES
No DBUG_ENTER... here to get smaller dbug-startup
*/
void* my_once_alloc(size_t Size, myf MyFlags)
{
size_t get_size, max_left;
uchar* point;
reg1 USED_MEM *next;
reg2 USED_MEM **prev;
Size= ALIGN_SIZE(Size);
prev= &my_once_root_block;
max_left=0;
for (next=my_once_root_block ; next && next->left < Size ; next= next->next)
{
if (next->left > max_left)
max_left=next->left;
prev= &next->next;
}
if (! next)
{ /* Time to alloc new block */
get_size= Size+ALIGN_SIZE(sizeof(USED_MEM));
if (max_left*4 < my_once_extra && get_size < my_once_extra)
get_size=my_once_extra; /* Normal alloc */
if ((next = (USED_MEM*) malloc(get_size)) == 0)
{
my_errno=errno;
if (MyFlags & (MY_FAE+MY_WME))
my_error(EE_OUTOFMEMORY, MYF(ME_BELL+ME_WAITTANG+ME_FATALERROR), get_size);
return((uchar*) 0);
}
DBUG_PRINT("test",("my_once_malloc %lu byte malloced", (ulong) get_size));
next->next= 0;
next->size= get_size;
next->left= get_size-ALIGN_SIZE(sizeof(USED_MEM));
*prev=next;
}
point= (uchar*) ((char*) next+ (next->size-next->left));
next->left-= Size;
if (MyFlags & MY_ZEROFILL)
bzero(point, Size);
return((void*) point);
} /* my_once_alloc */
char *my_once_strdup(const char *src,myf myflags)
{
size_t len= strlen(src)+1;
uchar *dst= my_once_alloc(len, myflags);
if (dst)
memcpy(dst, src, len);
return (char*) dst;
}
void *my_once_memdup(const void *src, size_t len, myf myflags)
{
uchar *dst= my_once_alloc(len, myflags);
if (dst)
memcpy(dst, src, len);
return dst;
}
/*
Deallocate everything that was allocated with my_once_alloc
SYNOPSIS
my_once_free()
*/
void my_once_free(void)
{
reg1 USED_MEM *next,*old;
DBUG_ENTER("my_once_free");
for (next=my_once_root_block ; next ; )
{
old=next; next= next->next ;
free((uchar*) old);
}
my_once_root_block=0;
DBUG_VOID_RETURN;
} /* my_once_free */