bug report

["Manuel Alguacil Payán" <mapmail@iespana.es>]

[-- Attachment #1: Type: text/plain, Size: 2190 bytes --]

Hello, my name is Manuel Alguacil and this message is about a possible 
gcc/g++ bug. I am Computer Engeenering and I use to compile C programs
under 
Linux using the Gnu C Compiler (version 3.2 release 7). Actually I am
using
Red Hat 8.0 with an AMD Athlon 500Mhz, but you can find the whole
configuration
described in the 'dmesg.txt' file.

Some days ago I started a program and I found some troubles while trying
to use
a dinamic matrix. I was reciving a 'Segmentation fault' error. In the
beginning
I thought it could be produced by a bad data manipulation by me, but
making some
probes, I finally reach this conclusion: The gcc compiler is not
treating
correctly the dinamic matrix. I include in this message two code files:
one 
with the error and other with the "correct runnable code". Both codes
compile 
perfectly, but the first one gives the error, and the other one patchs
it (but 
this is a very poor solution). Anyway, this solution only works with a
small 
matrix. If we try to use a bigger one, it gives the same error.

The problem is as follows: I am mannaging a two dimensions matrix
dinamically, 
and after a lot of probes I think the problem is that the 'calloc' call
doesn't
works fine, because the first row is not set to zero after 'calloc'. I 
think that malloc is in same way. You can see the output of the wrong
code in 
the 'out.txt' file. If you want to see the error, you only have to
uncomment the 
code of the wrong file (that fill the whole matrix) and you will see.

I don't really know if I was right sending this bug here. If not, please
excuse me and if you know who I have to write, tell me, ok?

Well, I tried to explain the best I can the problem. Please, forgive my
poor
english (I am Spanish). For any doub or suggest, please contact me at
<mapmail@iespana.es> or <manuel.alguacil.ext@juntadeandalucia.es>

I hope this e-mail will be useful for everyone. Thanks.

Manuel Alguacil Payan
Seville (Spain)

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[-- Attachment #2: dmesg.txt --]
[-- Type: text/plain, Size: 7324 bytes --]

Linux version 2.4.18-14smp (bhcompile@astest.test.redhat.com) (gcc version 3.2 20020903 (Red Hat Linux 8.0 3.2-7)) #1 SMP Wed Sep 4 11:55:37 EDT 2002
BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
 BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 0000000013ff0000 (usable)
 BIOS-e820: 0000000013ff0000 - 0000000013ff3000 (ACPI NVS)
 BIOS-e820: 0000000013ff3000 - 0000000014000000 (ACPI data)
 BIOS-e820: 00000000ffff0000 - 0000000100000000 (reserved)
0MB HIGHMEM available.
319MB LOWMEM available.
On node 0 totalpages: 81904
zone(0): 4096 pages.
zone(1): 77808 pages.
zone(2): 0 pages.
Kernel command line: auto BOOT_IMAGE=linux ro BOOT_FILE=/boot/vmlinuz-2.4.18-14smp root=LABEL=/
No local APIC present or hardware disabled
Initializing CPU#0
Detected 499.050 MHz processor.
Speakup v-1.00 CVS: Tue Jun 11 14:22:53 EDT 2002 : initialized
Console: colour VGA+ 80x25
Calibrating delay loop... 990.06 BogoMIPS
Memory: 316960k/327616k available (1426k kernel code, 8092k reserved, 1057k data, 240k init, 0k highmem)
Dentry cache hash table entries: 65536 (order: 7, 524288 bytes)
Inode cache hash table entries: 32768 (order: 6, 262144 bytes)
Mount cache hash table entries: 8192 (order: 4, 65536 bytes)
ramfs: mounted with options: <defaults>
ramfs: max_pages=39892 max_file_pages=0 max_inodes=0 max_dentries=39892
Buffer cache hash table entries: 16384 (order: 4, 65536 bytes)
Page-cache hash table entries: 131072 (order: 7, 524288 bytes)
CPU: Before vendor init, caps: 0081f9ff c0c1f9ff 00000000, vendor = 2
CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
CPU: L2 Cache: 512K (64 bytes/line)
CPU: After vendor init, caps: 0081f9ff c0c1f9ff 00000000 00000000
Intel machine check architecture supported.
Intel machine check reporting enabled on CPU#0.
CPU:     After generic, caps: 0081f9ff c0c1f9ff 00000000 00000000
CPU:             Common caps: 0081f9ff c0c1f9ff 00000000 00000000
Checking 'hlt' instruction... OK.
POSIX conformance testing by UNIFIX
mtrr: v1.40 (20010327) Richard Gooch (rgooch@atnf.csiro.au)
mtrr: detected mtrr type: Intel
CPU: Before vendor init, caps: 0081f9ff c0c1f9ff 00000000, vendor = 2
CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
CPU: L2 Cache: 512K (64 bytes/line)
CPU: After vendor init, caps: 0081f9ff c0c1f9ff 00000000 00000000
Intel machine check reporting enabled on CPU#0.
CPU:     After generic, caps: 0081f9ff c0c1f9ff 00000000 00000000
CPU:             Common caps: 0081f9ff c0c1f9ff 00000000 00000000
CPU0: AMD-K7(tm) Processor stepping 02
per-CPU timeslice cutoff: 1461.94 usecs.
task migration cache decay timeout: 1 msecs.
SMP motherboard not detected.
Local APIC not detected. Using dummy APIC emulation.
migration_task 0 on cpu=0
PCI: PCI BIOS revision 2.10 entry at 0xfb3c0, last bus=1
PCI: Using configuration type 1
PCI: Probing PCI hardware
Unknown bridge resource 0: assuming transparent
PCI: Using IRQ router default [1022/7006] at 00:00.0
isapnp: Scanning for PnP cards...
isapnp: No Plug & Play device found
speakup:  initialized device: /dev/synth, node (MAJOR 10, MINOR 25)
Linux NET4.0 for Linux 2.4
Based upon Swansea University Computer Society NET3.039
Initializing RT netlink socket
apm: BIOS version 1.2 Flags 0x07 (Driver version 1.16)
Starting kswapd
VFS: Diskquotas version dquot_6.5.0 initialized
pty: 2048 Unix98 ptys configured
Serial driver version 5.05c (2001-07-08) with MANY_PORTS MULTIPORT SHARE_IRQ SERIAL_PCI ISAPNP enabled
ttyS0 at 0x03f8 (irq = 4) is a 16550A
ttyS1 at 0x02f8 (irq = 3) is a 16550A
Real Time Clock Driver v1.10e
block: 608 slots per queue, batch=152
Uniform Multi-Platform E-IDE driver Revision: 6.31
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
AMD7409: IDE controller on PCI bus 00 dev 39
AMD7409: chipset revision 3
AMD7409: not 100% native mode: will probe irqs later
AMD7409: disabling single-word DMA support (revision < C4)
    ide0: BM-DMA at 0xf000-0xf007, BIOS settings: hda:DMA, hdb:DMA
    ide1: BM-DMA at 0xf008-0xf00f, BIOS settings: hdc:DMA, hdd:pio
hda: ST320413A, ATA DISK drive
hdb: LG CD-ROM CRD-8521B, ATAPI CD/DVD-ROM drive
hdc: SAMSUNG SV0432A 024, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
blk: queue c0435b64, I/O limit 4095Mb (mask 0xffffffff)
blk: queue c0435b64, I/O limit 4095Mb (mask 0xffffffff)
hda: setmax LBA 39102337, native  39102336
hda: 39102336 sectors (20020 MB) w/1024KiB Cache, CHS=2434/255/63, UDMA(33)
blk: queue c0435ec0, I/O limit 4095Mb (mask 0xffffffff)
blk: queue c0435ec0, I/O limit 4095Mb (mask 0xffffffff)
hdc: 8421840 sectors (4312 MB) w/482KiB Cache, CHS=8912/15/63, UDMA(33)
ide-floppy driver 0.99.newide
Partition check:
 hda: hda1 hda2 hda4 < hda5 hda6 >
 hdc: [PTBL] [524/255/63] hdc1
Floppy drive(s): fd0 is 1.44M
FDC 0 is a post-1991 82077
NET4: Frame Diverter 0.46
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
ide-floppy driver 0.99.newide
md: md driver 0.90.0 MAX_MD_DEVS=256, MD_SB_DISKS=27
md: Autodetecting RAID arrays.
md: autorun ...
md: ... autorun DONE.
NET4: Linux TCP/IP 1.0 for NET4.0
IP Protocols: ICMP, UDP, TCP, IGMP
IP: routing cache hash table of 2048 buckets, 16Kbytes
TCP: Hash tables configured (established 32768 bind 32768)
Linux IP multicast router 0.06 plus PIM-SM
NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
RAMDISK: Compressed image found at block 0
Freeing initrd memory: 131k freed
VFS: Mounted root (ext2 filesystem).
Journalled Block Device driver loaded
kjournald starting.  Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
Freeing unused kernel memory: 240k freed
usb.c: registered new driver usbdevfs
usb.c: registered new driver hub
usb-ohci.c: USB OHCI at membase 0xd484b000, IRQ 11
usb-ohci.c: usb-00:07.4, Advanced Micro Devices [AMD] AMD-756 [Viper] USB
usb-ohci.c: AMD756 erratum 4 workaround
usb.c: new USB bus registered, assigned bus number 1
hub.c: USB hub found
hub.c: 4 ports detected
usb.c: registered new driver hiddev
usb.c: registered new driver hid
hid-core.c: v1.8.1 Andreas Gal, Vojtech Pavlik <vojtech@suse.cz>
hid-core.c: USB HID support drivers
mice: PS/2 mouse device common for all mice
EXT3 FS 2.4-0.9.18, 14 May 2002 on ide0(3,1), internal journal
Adding Swap: 104380k swap-space (priority -1)
kjournald starting.  Commit interval 5 seconds
EXT3 FS 2.4-0.9.18, 14 May 2002 on ide0(3,5), internal journal
EXT3-fs: mounted filesystem with ordered data mode.
parport0: PC-style at 0x378 (0x778) [PCSPP,TRISTATE,EPP]
parport0: irq 7 detected
ohci1394: pci_module_init failed
ip_tables: (C) 2000-2002 Netfilter core team
es1371: version v0.30 time 12:07:55 Sep  4 2002
es1371: found chip, vendor id 0x1274 device id 0x1371 revision 0x06
es1371: found es1371 rev 6 at io 0xe400 irq 10
es1371: features: joystick 0x0
ac97_codec: AC97 Audio codec, id: 0x8384:0x7609 (SigmaTel STAC9721/23)
ide-floppy driver 0.99.newide
hdb: ATAPI 52X CD-ROM drive, 128kB Cache
Uniform CD-ROM driver Revision: 3.12
cdrom: This disc doesn't have any tracks I recognize!

[-- Attachment #3: wrong.c --]
[-- Type: application/octet-stream, Size: 473 bytes --]

#include <stdio.h>
#include <stdlib.h>

#define F	5
#define C	5

int main()
{
	int 	i,j;
	char ** a;

	a=(char **) calloc(F, sizeof(char));
	for(i=0; i<F; i++) {
		*(a+i)=(char *) calloc(C, sizeof(char));
		if( *(a+i) == NULL ) {
			printf("Calloc Failure\n");
			exit(1);
		}
	}

	for(i=0; i<F; i++) {
		for(j=0; j<C; j++) printf("%i  ", a[i][j]);
		putchar('\n');
	}

/*	for(i=0; i<F; i++)
		for(j=0; j<C; j++) a[i][j]='x'; */

	return 0;
}

[-- Attachment #4: out.txt --]
[-- Type: text/plain, Size: 91 bytes --]

-120  -106  4  8  0  
0  0  0  0  0  
0  0  0  0  0  
0  0  0  0  0  
0  0  0  0  0  

[-- Attachment #5: fine.c --]
[-- Type: application/octet-stream, Size: 512 bytes --]

#include <stdio.h>
#include <stdlib.h>

#define F	5
#define C	5

int main()
{
	int 	i,j;
	char ** a;

	a=(char **) calloc(F, sizeof(char));
	for(i=0; i<F; i++) {
		*(a+i)=(char *) calloc(C, sizeof(char));
		*(a+i)=(char *) calloc(C, sizeof(char));
		if( *(a+i) == NULL ) {
			printf("Calloc Failure\n");
			exit(1);
		}
	}

	for(i=0; i<F; i++) {
		for(j=0; j<C; j++) printf("%i  ", a[i][j]);
		putchar('\n');
	}

	for(i=0; i<F; i++)
		for(j=0; j<C; j++) a[i][j]='x';

	return 0;
}