Subject: new kernel oops in recent kernels

From: Giuseppe Sacco <[email-masked]>
Date: Sun, 16 Mar 2008 11:49:23 +0100

Hi all,
testing the latest kernels on SGI O2, I found this new kernel oops. It
is there (even if code changed a bit) since 2.6.22, but the oops I
attach here has been produced with kernel from linux-mips.org git of
yesterday night.

I don't know if this is a problem that I should report to this list, or
if I should address a different list. If you have any suggestion, please
let me know.

Thanks a lot,
Giuseppe

CPU 0 Unable to handle kernel paging request at virtual address 0000000000000000, epc == 0000000000000000, ra == 0000000000000000
Oops[#1]:
Cpu 0
$ 0   : 0000000000000000 ffffffff9001fce0 ffffffffffffff86 0000000000000028
$ 4   : 980000000fc01140 0000000000000080 0000000000024000 0000000000000000
$ 8   : 980000000fc54700 0000000000000001 0000000000008000 404000130a0808ff
$12   : 0000000000000008 ffffffff801b8db8 0000000000000000 ffffffff803f0000
$16   : 980000000ff2fa70 980000000c417bb8 980000000c417c20 980000000fdeb610
$20   : 000000007fffffff 980000000f9211a0 980000000fc26000 000000007fa51ecd
$24   : 0000000000000000 ffffffff80074290                                  
$28   : 980000000c414000 980000000c417bb0 0000000000400000 0000000000000000
Hi    : 0000000000000000
Lo    : 003d08dbda057200
epc   : 0000000000000000 0x0     Not tainted
ra    : 0000000000000000 0x0
Status: 9001fce3    KX SX UX KERNEL EXL IE 
Cause : 00000008
BadVA : 0000000000000000
PrId  : 00002321 (R5000)
Modules linked in: parport_pc lp parport ipv6 deflate zlib_deflate ctr twofish twofish_common camellia serpent blowfish des_generic cbc aes_generic xcbc sha25
6_generic sha1_generic crypto_null crypto_blkcipher dm_snapshot dm_mirror dm_mod ehci_hcd ohci_hcd r8169 usbcore sg evdev
Process hald-probe-stor (pid: 1937, threadinfo=980000000c414000, task=980000000ebf47d8)
Stack : 980000000c417be0 980000000c417de0 0800000000000000 980000000c417bb0
        00000008ffffff86 0000000000000000 0200000000000001 000006d600000000
        0000000000000000 980000000c417de0 980000000fdeb610 0000000000000001
        0000000000005326 ffffffff802460b0 0000000070023a00 000000000f9211a0
        ffffffff80490000 ffffffff8024bb84 980000000fc10e80 980000000f80bb28
        0000000000000000 980000000f9210e0 0000010100000001 00000000800d1618
        0000000000000004 980000000fc8f850 000000007fffffff 980000000fde4000
        0000000000005326 000000007fffffff 980000000c407540 980000000f9211a0
        980000000fc26000 000000007fa51ecd ffffffff80245c6c 980000000c407540
        0000000000000000 fffffffffffffdfd 0000000000005326 ffffffff801ad8bc
        ...
Call Trace:
[<ffffffff802460b0>] sr_drive_status+0x50/0xe8
[<ffffffff8024bb84>] cdrom_ioctl+0x5f4/0x1208
[<ffffffff80245c6c>] sr_block_ioctl+0x64/0xe8
[<ffffffff801ad8bc>] compat_blkdev_ioctl+0x7cc/0x18e0
[<ffffffff800d1870>] do_open+0x98/0x310
[<ffffffff800d1d60>] blkdev_open+0x0/0xc0
[<ffffffff800d1da8>] blkdev_open+0x48/0xc0
[<ffffffff8009c444>] __dentry_open+0x114/0x2e0
[<ffffffff8009c740>] do_filp_open+0x48/0x58
[<ffffffff8009c740>] do_filp_open+0x48/0x58
[<ffffffff800def8c>] compat_sys_ioctl+0xf4/0x440
[<ffffffff80019154>] handle_sys+0x114/0x130
[<ffffffff8001fcf3>] fpu_emulator_cop1Handler+0x362/0x2270

Code: (Bad address in epc)

---

From: Giuseppe Sacco <[email-masked]>
Date: Sun, 16 Mar 2008 21:27:37 +0100

Hi all,
the Oops I reported earlier today, may be related to a problem of the
GNU C compiler, but I do not know MIPS assembly, so I ask for help.

> [<ffffffff8001fcf3>] fpu_emulator_cop1Handler+0x362/0x2270

sr_drive_status+0x50 is, in decimal, sr_drive_status+80
The gdb disassable the code as this:

(gdb) disassemble sr_drive_status+0x50
Dump of assembler code for function sr_drive_status:
0xffffffff80246060 <sr_drive_status+0>: daddiu  sp,sp,-32
0xffffffff80246064 <sr_drive_status+4>: lui     v0,0x7fff
0xffffffff80246068 <sr_drive_status+8>: sd      s0,16(sp)
0xffffffff8024606c <sr_drive_status+12>:        sd      ra,24(sp)
0xffffffff80246070 <sr_drive_status+16>:        ori     v0,v0,0xffff
0xffffffff80246074 <sr_drive_status+20>:        move    s0,a0
0xffffffff80246078 <sr_drive_status+24>:        bne     a1,v0,0xffffffff802460e8 <sr_drive_status+136>
0xffffffff8024607c <sr_drive_status+28>:        ld      v1,24(a0)
0xffffffff80246080 <sr_drive_status+32>:        ld      a0,16(v1)
0xffffffff80246084 <sr_drive_status+36>:        jal     0xffffffff80244c70 <sr_test_unit_ready>
0xffffffff80246088 <sr_drive_status+40>:        daddiu  a1,sp,4
0xffffffff8024608c <sr_drive_status+44>:        bnez    v0,0xffffffff802460a8 <sr_drive_status+72>
0xffffffff80246090 <sr_drive_status+48>:        move    a0,s0
0xffffffff80246094 <sr_drive_status+52>:        li      v0,4
0xffffffff80246098 <sr_drive_status+56>:        ld      ra,24(sp)
0xffffffff8024609c <sr_drive_status+60>:        ld      s0,16(sp)
0xffffffff802460a0 <sr_drive_status+64>:        jr      ra
0xffffffff802460a4 <sr_drive_status+68>:        daddiu  sp,sp,32
0xffffffff802460a8 <sr_drive_status+72>:        jal     0xffffffff8024c838 <cdrom_get_media_event>
0xffffffff802460ac <sr_drive_status+76>:        move    a1,sp
0xffffffff802460b0 <sr_drive_status+80>:        bnez    v0,0xffffffff802460fc <sr_drive_status+156>
0xffffffff802460b4 <sr_drive_status+84>:        lhu     v0,0(sp)
0xffffffff802460b8 <sr_drive_status+88>:        sll     v0,v0,0x0
0xffffffff802460bc <sr_drive_status+92>:        andi    v0,v0,0xff
0xffffffff802460c0 <sr_drive_status+96>:        andi    v1,v0,0x2
0xffffffff802460c4 <sr_drive_status+100>:       bnez    v1,0xffffffff80246094 <sr_drive_status+52>
0xffffffff802460c8 <sr_drive_status+104>:       andi    v0,v0,0x1
0xffffffff802460cc <sr_drive_status+108>:       beqz    v0,0xffffffff80246098 <sr_drive_status+56>
0xffffffff802460d0 <sr_drive_status+112>:       li      v0,1
0xffffffff802460d4 <sr_drive_status+116>:       ld      ra,24(sp)

then, I changed the code in sr_drive_status, adding the printk line, as
shown below:

int sr_drive_status(struct cdrom_device_info *cdi, int slot)
{
        struct scsi_cd *cd = cdi->handle;
        struct scsi_sense_hdr sshdr;
        struct media_event_desc med;

        if (CDSL_CURRENT != slot) {
                /* we have no changer support */
                return -EINVAL;
        }
        if (0 == sr_test_unit_ready(cd->device, &sshdr))
                return CDS_DISC_OK;

printk(KERN_INFO "sr_drive_status() cdi=0x%p, cd=0x%p\n", cdi, cd);

        if (!cdrom_get_media_event(cdi, &med)) {
                if (med.media_present)
                        return CDS_DISC_OK;
[...]

and now, I cannot reproduce any oops.

The new assembly code is:

0xffffffff80246060 <sr_drive_status+0>: daddiu  sp,sp,-48
0xffffffff80246064 <sr_drive_status+4>: lui     v0,0x7fff
0xffffffff80246068 <sr_drive_status+8>: sd      s0,16(sp)
0xffffffff8024606c <sr_drive_status+12>:        sd      ra,32(sp)
0xffffffff80246070 <sr_drive_status+16>:        sd      s1,24(sp)
0xffffffff80246074 <sr_drive_status+20>:        ori     v0,v0,0xffff
0xffffffff80246078 <sr_drive_status+24>:        move    s0,a0
0xffffffff8024607c <sr_drive_status+28>:        bne     a1,v0,0xffffffff80246108 <sr_drive_status+168>
0xffffffff80246080 <sr_drive_status+32>:        ld      s1,24(a0)
0xffffffff80246084 <sr_drive_status+36>:        ld      a0,16(s1)
0xffffffff80246088 <sr_drive_status+40>:        jal     0xffffffff80244c70 <sr_test_unit_ready>
0xffffffff8024608c <sr_drive_status+44>:        daddiu  a1,sp,4
0xffffffff80246090 <sr_drive_status+48>:        bnez    v0,0xffffffff802460b0 <sr_drive_status+80>
0xffffffff80246094 <sr_drive_status+52>:        lui     a0,0x803c
0xffffffff80246098 <sr_drive_status+56>:        li      v0,4
0xffffffff8024609c <sr_drive_status+60>:        ld      ra,32(sp)
0xffffffff802460a0 <sr_drive_status+64>:        ld      s1,24(sp)
0xffffffff802460a4 <sr_drive_status+68>:        ld      s0,16(sp)
0xffffffff802460a8 <sr_drive_status+72>:        jr      ra
0xffffffff802460ac <sr_drive_status+76>:        daddiu  sp,sp,48
0xffffffff802460b0 <sr_drive_status+80>:        daddiu  a0,a0,-4560
0xffffffff802460b4 <sr_drive_status+84>:        move    a1,s0
0xffffffff802460b8 <sr_drive_status+88>:        jal     0xffffffff80032ba8 <printk>
0xffffffff802460bc <sr_drive_status+92>:        move    a2,s1
0xffffffff802460c0 <sr_drive_status+96>:        move    a0,s0
0xffffffff802460c4 <sr_drive_status+100>:       jal     0xffffffff8024c858 <cdrom_get_media_event>
0xffffffff802460c8 <sr_drive_status+104>:       move    a1,sp
0xffffffff802460cc <sr_drive_status+108>:       bnez    v0,0xffffffff80246120 <sr_drive_status+192>
0xffffffff802460d0 <sr_drive_status+112>:       lhu     v0,0(sp)

the gcc I am using in versione 4.1.2. Any help is really appreciated.

Thanks,
Giuseppe

---

From: [email-masked] (Thomas Bogendoerfer)
Date: Mon, 17 Mar 2008 00:36:19 +0100

> the gcc I am using in versione 4.1.2. Any help is really appreciated.

4.2.1 generates nearly the same (reasonable) code. The major difference
between the version with printk and the version without is the size
of the local stack. I guess this prevents killing of *cd.
Could you try the hack below and tell me, if it helps ? This hack
ensures, that the buffer given to the scsi driver is one cache
line big (at least on R5k O2s). If this helps, there are more
places to fix for non-coherent machines...

Thomas.

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 12f5bae..acb98a8 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -482,7 +482,7 @@ int cdrom_get_media_event(struct cdrom_device_info *cdi,
 			  struct media_event_desc *med)
 {
 	struct packet_command cgc;
-	unsigned char buffer[8];
+	unsigned char buffer[32];
 	struct event_header *eh = (struct event_header *) buffer;
 
 	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessary a
good idea.                                                [ RFC1925, 2.3 ]

---

From: Giuseppe Sacco <[email-masked]>
Date: Mon, 17 Mar 2008 09:05:42 +0100

Hi Thomas,

Il giorno lun, 17/03/2008 alle 00.36 +0100, Thomas Bogendoerfer ha
[...]

The patch you proposed, that use a larger buffer, does not seems to
trigger the bug.

Thanks,
Giuseppe

---

From: Ralf Baechle <[email-masked]>
Date: Mon, 17 Mar 2008 14:18:28 +0000

> The patch you proposed, that use a larger buffer, does not seems to

It may help but doesn't have a chance to be accepted upstream.  So
this is no more than an useful litmus test.

  Ralf

---

From: [email-masked] (Thomas Bogendoerfer)
Date: Mon, 17 Mar 2008 15:32:15 +0100

> this is no more than an useful litmus test.

sure, that's why I called it a hack. It was just to make sure, that I'm
on the right track.

Thomas.

---

From: [email-masked] (Thomas Bogendoerfer)
Date: Sat, 22 Mar 2008 00:00:10 +0100

> sure, that's why I called it a hack. It was just to make sure, that I'm

below is a patch, which replaces all buffers on the stack, which are
passed to the scsi layer with kmalloced ones.

Giuseppe, could you please check if this fixes your problem, and
doesn't cause new regressions ? 

Thomas.

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 12f5bae..fd45563 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -482,27 +482,37 @@ int cdrom_get_media_event(struct cdrom_device_info *cdi,
 			  struct media_event_desc *med)
 {
 	struct packet_command cgc;
-	unsigned char buffer[8];
-	struct event_header *eh = (struct event_header *) buffer;
+	unsigned char *buffer;
+	struct event_header *eh;
+	int ret = 1;
+
+	buffer = kmalloc(8, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
 
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
+	eh = (struct event_header *)buffer;
+
+	init_cdrom_command(&cgc, buffer, 8, CGC_DATA_READ);
 	cgc.cmd[0] = GPCMD_GET_EVENT_STATUS_NOTIFICATION;
 	cgc.cmd[1] = 1;		/* IMMED */
 	cgc.cmd[4] = 1 << 4;	/* media event */
-	cgc.cmd[8] = sizeof(buffer);
+	cgc.cmd[8] = 8;
 	cgc.quiet = 1;
 
 	if (cdi->ops->generic_packet(cdi, &cgc))
-		return 1;
+		goto err;
 
 	if (be16_to_cpu(eh->data_len) < sizeof(*med))
-		return 1;
+		goto err;
 
 	if (eh->nea || eh->notification_class != 0x4)
-		return 1;
+		goto err;
 
-	memcpy(med, &buffer[sizeof(*eh)], sizeof(*med));
-	return 0;
+	memcpy(med, buffer + sizeof(*eh), sizeof(*med));
+	ret = 0;
+err:
+	kfree(buffer);
+	return ret;
 }
 
 /*
@@ -512,68 +522,82 @@ int cdrom_get_media_event(struct cdrom_device_info *cdi,
 static int cdrom_mrw_probe_pc(struct cdrom_device_info *cdi)
 {
 	struct packet_command cgc;
-	char buffer[16];
+	char *buffer;
+	int ret = 1;
+
+	buffer = kmalloc(16, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
 
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
+	init_cdrom_command(&cgc, buffer, 16, CGC_DATA_READ);
 
 	cgc.timeout = HZ;
 	cgc.quiet = 1;
 
 	if (!cdrom_mode_sense(cdi, &cgc, MRW_MODE_PC, 0)) {
 		cdi->mrw_mode_page = MRW_MODE_PC;
-		return 0;
+		ret = 0;
 	} else if (!cdrom_mode_sense(cdi, &cgc, MRW_MODE_PC_PRE1, 0)) {
 		cdi->mrw_mode_page = MRW_MODE_PC_PRE1;
-		return 0;
+		ret = 0;
 	}
-
-	return 1;
+	kfree(buffer);
+	return ret;
 }
 
 static int cdrom_is_mrw(struct cdrom_device_info *cdi, int *write)
 {
 	struct packet_command cgc;
 	struct mrw_feature_desc *mfd;
-	unsigned char buffer[16];
+	unsigned char *buffer;
 	int ret;
 
 	*write = 0;
+	buffer = kmalloc(16, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
 
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
+	init_cdrom_command(&cgc, buffer, 16, CGC_DATA_READ);
 
 	cgc.cmd[0] = GPCMD_GET_CONFIGURATION;
 	cgc.cmd[3] = CDF_MRW;
-	cgc.cmd[8] = sizeof(buffer);
+	cgc.cmd[8] = 16;
 	cgc.quiet = 1;
 
 	if ((ret = cdi->ops->generic_packet(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	mfd = (struct mrw_feature_desc *)&buffer[sizeof(struct feature_header)];
-	if (be16_to_cpu(mfd->feature_code) != CDF_MRW)
-		return 1;
+	if (be16_to_cpu(mfd->feature_code) != CDF_MRW) {
+		ret = 1;
+		goto err;
+	}
 	*write = mfd->write;
 
 	if ((ret = cdrom_mrw_probe_pc(cdi))) {
 		*write = 0;
-		return ret;
 	}
-
-	return 0;
+err:
+	kfree(buffer);
+	return ret;
 }
 
 static int cdrom_mrw_bgformat(struct cdrom_device_info *cdi, int cont)
 {
 	struct packet_command cgc;
-	unsigned char buffer[12];
+	unsigned char *buffer;
 	int ret;
 
 	printk(KERN_INFO "cdrom: %sstarting format\n", cont ? "Re" : "");
 
+	buffer = kmalloc(12, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
 	/*
 	 * FmtData bit set (bit 4), format type is 1
 	 */
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_WRITE);
+	init_cdrom_command(&cgc, buffer, 12, CGC_DATA_WRITE);
 	cgc.cmd[0] = GPCMD_FORMAT_UNIT;
 	cgc.cmd[1] = (1 << 4) | 1;
 
@@ -600,6 +624,7 @@ static int cdrom_mrw_bgformat(struct cdrom_device_info *cdi, int cont)
 	if (ret)
 		printk(KERN_INFO "cdrom: bgformat failed\n");
 
+	kfree(buffer);
 	return ret;
 }
 
@@ -659,16 +684,17 @@ static int cdrom_mrw_set_lba_space(struct cdrom_device_info *cdi, int space)
 {
 	struct packet_command cgc;
 	struct mode_page_header *mph;
-	char buffer[16];
+	char *buffer;
 	int ret, offset, size;
 
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
+	buffer = kmalloc(16, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
 
-	cgc.buffer = buffer;
-	cgc.buflen = sizeof(buffer);
+	init_cdrom_command(&cgc, buffer, 16, CGC_DATA_READ);
 
 	if ((ret = cdrom_mode_sense(cdi, &cgc, cdi->mrw_mode_page, 0)))
-		return ret;
+		goto err;
 
 	mph = (struct mode_page_header *) buffer;
 	offset = be16_to_cpu(mph->desc_length);
@@ -678,55 +704,70 @@ static int cdrom_mrw_set_lba_space(struct cdrom_device_info *cdi, int space)
 	cgc.buflen = size;
 
 	if ((ret = cdrom_mode_select(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	printk(KERN_INFO "cdrom: %s: mrw address space %s selected\n", cdi->name, mrw_address_space[space]);
-	return 0;
+	ret = 0;
+err:
+	kfree(buffer);
+	return ret;
 }
 
 static int cdrom_get_random_writable(struct cdrom_device_info *cdi,
 			      struct rwrt_feature_desc *rfd)
 {
 	struct packet_command cgc;
-	char buffer[24];
+	char *buffer;
 	int ret;
 
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
+	buffer = kmalloc(24, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	init_cdrom_command(&cgc, buffer, 24, CGC_DATA_READ);
 
 	cgc.cmd[0] = GPCMD_GET_CONFIGURATION;	/* often 0x46 */
 	cgc.cmd[3] = CDF_RWRT;			/* often 0x0020 */
-	cgc.cmd[8] = sizeof(buffer);		/* often 0x18 */
+	cgc.cmd[8] = 24;		        /* often 0x18 */
 	cgc.quiet = 1;
 
 	if ((ret = cdi->ops->generic_packet(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	memcpy(rfd, &buffer[sizeof(struct feature_header)], sizeof (*rfd));
-	return 0;
+	ret = 0;
+err:
+	kfree(buffer);
+	return ret;
 }
 
 static int cdrom_has_defect_mgt(struct cdrom_device_info *cdi)
 {
 	struct packet_command cgc;
-	char buffer[16];
+	char *buffer;
 	__be16 *feature_code;
 	int ret;
 
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
+	buffer = kmalloc(16, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	init_cdrom_command(&cgc, buffer, 16, CGC_DATA_READ);
 
 	cgc.cmd[0] = GPCMD_GET_CONFIGURATION;
 	cgc.cmd[3] = CDF_HWDM;
-	cgc.cmd[8] = sizeof(buffer);
+	cgc.cmd[8] = 16;
 	cgc.quiet = 1;
 
 	if ((ret = cdi->ops->generic_packet(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	feature_code = (__be16 *) &buffer[sizeof(struct feature_header)];
 	if (be16_to_cpu(*feature_code) == CDF_HWDM)
-		return 0;
-
-	return 1;
+		ret = 0;
+err:
+	kfree(buffer);
+	return ret;
 }

@@ -817,10 +858,14 @@ static int cdrom_mrw_open_write(struct cdrom_device_info *cdi)
 static int mo_open_write(struct cdrom_device_info *cdi)
 {
 	struct packet_command cgc;
-	char buffer[255];
+	char *buffer;
 	int ret;
 
-	init_cdrom_command(&cgc, &buffer, 4, CGC_DATA_READ);
+	buffer = kmalloc(255, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	init_cdrom_command(&cgc, buffer, 4, CGC_DATA_READ);
 	cgc.quiet = 1;
 
 	/*
@@ -837,10 +882,15 @@ static int mo_open_write(struct cdrom_device_info *cdi)
 	}
 
 	/* drive gave us no info, let the user go ahead */
-	if (ret)
-		return 0;
+	if (ret) {
+		ret = 0;
+		goto err;
+	}
 
-	return buffer[3] & 0x80;
+	ret = buffer[3] & 0x80;
+err:
+	kfree(buffer);
+	return ret;
 }
 
 static int cdrom_ram_open_write(struct cdrom_device_info *cdi)
@@ -863,15 +913,19 @@ static int cdrom_ram_open_write(struct cdrom_device_info *cdi)
 static void cdrom_mmc3_profile(struct cdrom_device_info *cdi)
 {
 	struct packet_command cgc;
-	char buffer[32];
+	char *buffer;
 	int ret, mmc3_profile;
 
-	init_cdrom_command(&cgc, buffer, sizeof(buffer), CGC_DATA_READ);
+	buffer = kmalloc(32, GFP_KERNEL);
+	if (!buffer)
+		return;
+
+	init_cdrom_command(&cgc, buffer, 32, CGC_DATA_READ);
 
 	cgc.cmd[0] = GPCMD_GET_CONFIGURATION;
 	cgc.cmd[1] = 0;
 	cgc.cmd[2] = cgc.cmd[3] = 0;		/* Starting Feature Number */
-	cgc.cmd[8] = sizeof(buffer);		/* Allocation Length */
+	cgc.cmd[8] = 32;		        /* Allocation Length */
 	cgc.quiet = 1;
 
 	if ((ret = cdi->ops->generic_packet(cdi, &cgc)))
@@ -880,6 +934,7 @@ static void cdrom_mmc3_profile(struct cdrom_device_info *cdi)
 		mmc3_profile = (buffer[6] << 8) | buffer[7];
 
 	cdi->mmc3_profile = mmc3_profile;
+	kfree(buffer);
 }
 
 static int cdrom_is_dvd_rw(struct cdrom_device_info *cdi)
@@ -1594,12 +1649,15 @@ static void setup_send_key(struct packet_command *cgc, unsigned agid, unsigned t
 static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 {
 	int ret;
-	u_char buf[20];
+	u_char *buf;
 	struct packet_command cgc;
 	struct cdrom_device_ops *cdo = cdi->ops;
-	rpc_state_t rpc_state;
+	rpc_state_t *rpc_state;
+
+	buf = kzalloc(20, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	memset(buf, 0, sizeof(buf));
 	init_cdrom_command(&cgc, buf, 0, CGC_DATA_READ);
 
 	switch (ai->type) {
@@ -1610,7 +1668,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		setup_report_key(&cgc, ai->lsa.agid, 0);
 
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 
 		ai->lsa.agid = buf[7] >> 6;
 		/* Returning data, let host change state */
@@ -1621,7 +1679,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		setup_report_key(&cgc, ai->lsk.agid, 2);
 
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 
 		copy_key(ai->lsk.key, &buf[4]);
 		/* Returning data, let host change state */
@@ -1632,7 +1690,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		setup_report_key(&cgc, ai->lsc.agid, 1);
 
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 
 		copy_chal(ai->lsc.chal, &buf[4]);
 		/* Returning data, let host change state */
@@ -1649,7 +1707,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		cgc.cmd[2] = ai->lstk.lba >> 24;
 
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 
 		ai->lstk.cpm = (buf[4] >> 7) & 1;
 		ai->lstk.cp_sec = (buf[4] >> 6) & 1;
@@ -1663,7 +1721,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		setup_report_key(&cgc, ai->lsasf.agid, 5);
 		
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 
 		ai->lsasf.asf = buf[7] & 1;
 		break;
@@ -1676,7 +1734,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		copy_chal(&buf[4], ai->hsc.chal);
 
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 
 		ai->type = DVD_LU_SEND_KEY1;
 		break;
@@ -1689,7 +1747,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 
 		if ((ret = cdo->generic_packet(cdi, &cgc))) {
 			ai->type = DVD_AUTH_FAILURE;
-			return ret;
+			goto err;
 		}
 		ai->type = DVD_AUTH_ESTABLISHED;
 		break;
@@ -1700,24 +1758,23 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		cdinfo(CD_DVD, "entering DVD_INVALIDATE_AGID\n"); 
 		setup_report_key(&cgc, ai->lsa.agid, 0x3f);
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 		break;
 
 	/* Get region settings */
 	case DVD_LU_SEND_RPC_STATE:
 		cdinfo(CD_DVD, "entering DVD_LU_SEND_RPC_STATE\n");
 		setup_report_key(&cgc, 0, 8);
-		memset(&rpc_state, 0, sizeof(rpc_state_t));
-		cgc.buffer = (char *) &rpc_state;
 
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 
-		ai->lrpcs.type = rpc_state.type_code;
-		ai->lrpcs.vra = rpc_state.vra;
-		ai->lrpcs.ucca = rpc_state.ucca;
-		ai->lrpcs.region_mask = rpc_state.region_mask;
-		ai->lrpcs.rpc_scheme = rpc_state.rpc_scheme;
+		rpc_state = (rpc_state_t *)buf;
+		ai->lrpcs.type = rpc_state->type_code;
+		ai->lrpcs.vra = rpc_state->vra;
+		ai->lrpcs.ucca = rpc_state->ucca;
+		ai->lrpcs.region_mask = rpc_state->region_mask;
+		ai->lrpcs.rpc_scheme = rpc_state->rpc_scheme;
 		break;
 
 	/* Set region settings */
@@ -1728,20 +1785,23 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
 		buf[4] = ai->hrpcs.pdrc;
 
 		if ((ret = cdo->generic_packet(cdi, &cgc)))
-			return ret;
+			goto err;
 		break;
 
 	default:
 		cdinfo(CD_WARNING, "Invalid DVD key ioctl (%d)\n", ai->type);
-		return -ENOTTY;
+		ret = -ENOTTY;
+		goto err;
 	}
-
-	return 0;
+	ret = 0;
+err:
+	kfree(buf);
+	return ret;
 }
 
 static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s)
 {
-	unsigned char buf[21], *base;
+	unsigned char *buf, *base;
 	struct dvd_layer *layer;
 	struct packet_command cgc;
 	struct cdrom_device_ops *cdo = cdi->ops;
@@ -1750,7 +1810,11 @@ static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s)
 	if (layer_num >= DVD_LAYERS)
 		return -EINVAL;
 
-	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
+	buf = kmalloc(21, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	init_cdrom_command(&cgc, buf, 21, CGC_DATA_READ);
 	cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
 	cgc.cmd[6] = layer_num;
 	cgc.cmd[7] = s->type;
@@ -1762,7 +1826,7 @@ static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s)
 	cgc.quiet = 1;
 
 	if ((ret = cdo->generic_packet(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	base = &buf[4];
 	layer = &s->physical.layer[layer_num];
@@ -1786,17 +1850,24 @@ static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s)
 	layer->end_sector_l0 = base[13] << 16 | base[14] << 8 | base[15];
 	layer->bca = base[16] >> 7;
 
-	return 0;
+	ret = 0;
+err:
+	kfree(buf);
+	return ret;
 }
 
 static int dvd_read_copyright(struct cdrom_device_info *cdi, dvd_struct *s)
 {
 	int ret;
-	u_char buf[8];
+	u_char *buf;
 	struct packet_command cgc;
 	struct cdrom_device_ops *cdo = cdi->ops;
 
-	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
+	buf = kmalloc(8, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	init_cdrom_command(&cgc, buf, 8, CGC_DATA_READ);
 	cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
 	cgc.cmd[6] = s->copyright.layer_num;
 	cgc.cmd[7] = s->type;
@@ -1804,12 +1875,15 @@ static int dvd_read_copyright(struct cdrom_device_info *cdi, dvd_struct *s)
 	cgc.cmd[9] = cgc.buflen & 0xff;
 
 	if ((ret = cdo->generic_packet(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	s->copyright.cpst = buf[4];
 	s->copyright.rmi = buf[5];
 
-	return 0;
+	ret = 0;
+err:
+	kfree(buf);
+	return ret;
 }
 
 static int dvd_read_disckey(struct cdrom_device_info *cdi, dvd_struct *s)
@@ -1841,26 +1915,33 @@ static int dvd_read_disckey(struct cdrom_device_info *cdi, dvd_struct *s)
 static int dvd_read_bca(struct cdrom_device_info *cdi, dvd_struct *s)
 {
 	int ret;
-	u_char buf[4 + 188];
+	u_char *buf;
 	struct packet_command cgc;
 	struct cdrom_device_ops *cdo = cdi->ops;
 
-	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
+	buf = kmalloc(4 + 188, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	init_cdrom_command(&cgc, buf, 4 + 188, CGC_DATA_READ);
 	cgc.cmd[0] = GPCMD_READ_DVD_STRUCTURE;
 	cgc.cmd[7] = s->type;
 	cgc.cmd[9] = cgc.buflen & 0xff;
 
 	if ((ret = cdo->generic_packet(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	s->bca.len = buf[0] << 8 | buf[1];
 	if (s->bca.len < 12 || s->bca.len > 188) {
 		cdinfo(CD_WARNING, "Received invalid BCA length (%d)\n", s->bca.len);
-		return -EIO;
+		ret = -EIO;
+		goto err;
 	}
 	memcpy(s->bca.value, &buf[4], s->bca.len);
-
-	return 0;
+	ret = 0;
+err:
+	kfree(buf);
+	return ret;
 }
 
 static int dvd_read_manufact(struct cdrom_device_info *cdi, dvd_struct *s)
@@ -1960,9 +2041,13 @@ static int cdrom_read_subchannel(struct cdrom_device_info *cdi,
 {
 	struct cdrom_device_ops *cdo = cdi->ops;
 	struct packet_command cgc;
-	char buffer[32];
+	char *buffer;
 	int ret;
 
+	buffer = kmalloc(32, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
 	init_cdrom_command(&cgc, buffer, 16, CGC_DATA_READ);
 	cgc.cmd[0] = GPCMD_READ_SUBCHANNEL;
 	cgc.cmd[1] = 2;     /* MSF addressing */
@@ -1971,7 +2056,7 @@ static int cdrom_read_subchannel(struct cdrom_device_info *cdi,
 	cgc.cmd[8] = 16;
 
 	if ((ret = cdo->generic_packet(cdi, &cgc)))
-		return ret;
+		goto err;
 
 	subchnl->cdsc_audiostatus = cgc.buffer[1];
 	subchnl->cdsc_format = CDROM_MSF;
@@ -1986,7 +2071,10 @@ static int cdrom_read_subchannel(struct cdrom_device_info *cdi,
 	subchnl->cdsc_absaddr.msf.second = cgc.buffer[10];
 	subchnl->cdsc_absaddr.msf.frame = cgc.buffer[11];
 
-	return 0;
+	ret = 0;
+err:
+	kfree(buffer);
+	return ret;
 }
 
 /*

---

From: Giuseppe Sacco <[email-masked]>
Date: Sun, 23 Mar 2008 00:39:58 +0100

Hi Thomas,

Il giorno sab, 22/03/2008 alle 00.00 +0100, Thomas Bogendoerfer ha
scritto:
[...]
> doesn't cause new regressions ? 

I rebuilt a kernel (pulling latest code from git) with your patch. Now I
do not get anymore the Oops at boot time, moreover I may mount a CDROM
and copying data from that CDROM to local SCSI disk.

Bye,
Giuseppe

---

From: [email-masked] (Thomas Bogendoerfer)
Date: Sun, 23 Mar 2008 12:16:10 +0100

> and copying data from that CDROM to local SCSI disk.

great, thank you for testing. I'll submit the patch to the maintainer.

Thomas.