IDE/CDROM Oops at boot time without /proc

Hello,

Please note that using IDE CDRom without /proc support will result in Oops at boot time.

In drivers/cdrom/cdrom.c, the code is :

/* Make sure that /proc/sys/dev is there */
ctl_table cdrom_root_table[] = {

#ifdef CONFIG_PROC_FS
        {CTL_DEV, "dev", NULL, 0, 0555, cdrom_cdrom_table},
#endif /* CONFIG_PROC_FS */
        {0}
        };

static struct ctl_table_header *cdrom_sysctl_header;

static void cdrom_sysctl_register(void)

{
        static int initialized;

        if (initialized == 1)
                return;

        cdrom_sysctl_header = register_sysctl_table(cdrom_root_table,
1);
        cdrom_root_table->child->de->owner = THIS_MODULE;

        /* set the defaults */
        cdrom_sysctl_settings.autoclose = autoclose;
        cdrom_sysctl_settings.autoeject = autoeject;
        cdrom_sysctl_settings.debug = debug;
        cdrom_sysctl_settings.lock = lockdoor;
        cdrom_sysctl_settings.check = check_media_type;

        initialized = 1;
}

The line cdrom_root_table->child->de->owner = THIS_MODULE; (line 2582) is broken is CONFIG_PROC_FS is not defined, as this is resulting in the following Oops :

Unable to handle kernel NULL pointer dereference at virtual address

00000020
printing eip:
c032e12c
*pde = 00000000

Oops: 0000
CPU:    0
EIP:    0060:[<c032e12c>]    Not tainted
EFLAGS: 00010292

EIP is at cdrom_sysctl_register+0x2a/0x74
eax: 00000000 ebx: c04c3fe0 ecx: dfc8de80 edx: dfc8de84
esi: c04c4014 edi: dfcedcf4 ebp: c059f348 esp: dff8fef8
ds: 007b es: 007b ss: 0068
Process swapper (pid: 1, threadinfo=dff8e000 task=dff8c080)

Stack: c04cf120 00000001 c0329e43 c0465400 c059f358 00000001 dfde2037
c046eaa0 
       c02eb6ae dfcedcf4 00000001 dfcedcf4 dfcedc00 c059f348 dfd91080
dfcedc00 
       dff8e000 c02ebc31 c059f348 00000000 0000013c c04c3bc4 c02502c3
c04c3f08 
Call Trace:
 [<c0329e43>] register_cdrom+0x1f7/0x20e
 [<c02eb6ae>] ide_cdrom_setup+0x352/0x4ec
 [<c02ebc31>] ide_cdrom_attach+0x13f/0x24e
 [<c02502c3>] kobject_add+0x87/0xd6
 [<c0289f62>] devclass_add_driver+0x1e/0x9c
 [<c0250331>] kobject_register+0x1f/0x62
 [<c02898f8>] bus_add_driver+0x86/0xac
 [<c02e31c3>] ata_attach+0x5b/0x11c
 [<c02e3eba>] ide_register_driver+0xe6/0x102
 [<c02ebd4f>] ide_cdrom_init+0xf/0x16
 [<c010506f>] init+0x3d/0x15a
 [<c0105032>] init+0x0/0x15a
 [<c0108c11>] kernel_thread_helper+0x5/0xc

Code: 8b 40 20 c7 40 24 00 00 00 00 c7 05 24 3b 5a c0 01 00 00 00 
 <0>Kernel panic: Attempted to kill init!
 <0>Rebooting in 30 seconds..

decoded as :
9 [14:28] rol@donald:~> more oops-cdrom.decode
ksymoops 2.4.8 on i686 2.4.20. Options used
-v /usr/src/linux/vmlinux (specified)
-K (specified)
-L (specified)
-o /lib/modules/2.4.20/ (default)
-m /usr/src/linux/System.map (specified)

No modules in ksyms, skipping objects

Unable to handle kernel NULL pointer dereference at virtual address
00000020
c032e12c
*pde = 00000000
Oops: 0000
CPU:    0
EIP:    0060:[<c032e12c>]    Not tainted

Using defaults from ksymoops -t elf32-i386 -a i386
EFLAGS: 00010292
eax: 00000000 ebx: c04c3fe0 ecx: dfc8de80 edx: dfc8de84
esi: c04c4014 edi: dfcedcf4 ebp: c059f348 esp: dff8fef8
ds: 007b es: 007b ss: 0068

Stack: c04cf120 00000001 c0329e43 c0465400 c059f358 00000001 dfde2037
c046eaa0 
       c02eb6ae dfcedcf4 00000001 dfcedcf4 dfcedc00 c059f348 dfd91080
dfcedc00 
       dff8e000 c02ebc31 c059f348 00000000 0000013c c04c3bc4 c02502c3
c04c3f08 
Call Trace:
 [<c0329e43>] register_cdrom+0x1f7/0x20e
 [<c02eb6ae>] ide_cdrom_setup+0x352/0x4ec
 [<c02ebc31>] ide_cdrom_attach+0x13f/0x24e
 [<c02502c3>] kobject_add+0x87/0xd6
 [<c0289f62>] devclass_add_driver+0x1e/0x9c
 [<c0250331>] kobject_register+0x1f/0x62
 [<c02898f8>] bus_add_driver+0x86/0xac
 [<c02e31c3>] ata_attach+0x5b/0x11c
 [<c02e3eba>] ide_register_driver+0xe6/0x102
 [<c02ebd4f>] ide_cdrom_init+0xf/0x16
 [<c010506f>] init+0x3d/0x15a
 [<c0105032>] init+0x0/0x15a
 [<c0108c11>] kernel_thread_helper+0x5/0xc
Code: 8b 40 20 c7 40 24 00 00 00 00 c7 05 24 3b 5a c0 01 00 00 00 

Trace; c0329e43 <register_cdrom+1f7/20e>
Trace; c02eb6ae <ide_cdrom_setup+352/4ec>
Trace; c02ebc31 <ide_cdrom_attach+13f/24e>
Trace; c02502c3 <kobject_add+87/d6>
Trace; c0289f62 <devclass_add_driver+1e/9c>
Trace; c0250331 <kobject_register+1f/62>
Trace; c02898f8 <bus_add_driver+86/ac>
Trace; c02e31c3 <ata_attach+5b/11c>
Trace; c02e3eba <ide_register_driver+e6/102>
Trace; c02ebd4f <ide_cdrom_init+f/16>
Trace; c010506f <init+3d/15a>
Trace; c0105032 <init+0/15a>
Trace; c0108c11 <kernel_thread_helper+5/c>

Code; c032e12c <cdrom_sysctl_register+2a/74>
00000000 <_EIP>:
Code; c032e12c <cdrom_sysctl_register+2a/74> <=====
0: 8b 40 20 mov 0x20(%eax),%eax <=====
Code; c032e12f <cdrom_sysctl_register+2d/74>
3: c7 40 24 00 00 00 00 movl $0x0,0x24(%eax)
Code; c032e136 <cdrom_sysctl_register+34/74>
a: c7 05 24 3b 5a c0 01 movl $0x1,0xc05a3b24
Code; c032e13d <cdrom_sysctl_register+3b/74>
11: 00 00 00

<0>Kernel panic: Attempted to kill init!

One easy trick would be to have :

#ifdef CONFIG_PROC_FS
        cdrom_root_table->child->de->owner = THIS_MODULE;

#endif

but as this doesn't seem to be the favorite approach from people on the mailing list, I'll leave this one to people in charge of the module to apply the best approach patch to fix this.

Please note that, however, I've tested this change, and it is working fine on my machine.

Regards,
Paul Rolland, [email protected]

Thanks for the raport, the proposed change is fine with me. Care to generate a real patch?

Jens Axboe

Hellon

Here it is :

4 [14:52] rol@donald:/kernels> diff -uN linux-2.5.56/drivers/cdrom/cdrom.c linux-2.5.56-work/drivers/cdrom/cdrom.c
--- linux-2.5.56/drivers/cdrom/cdrom.c 2003-01-10 21:11:26.000000000 +0100
+++ linux-2.5.56-work/drivers/cdrom/cdrom.c 2003-01-12
14:30:55.000000000 +0100
@@ -2579,7 +2579,9 @@
return;

cdrom_sysctl_header = register_sysctl_table(cdrom_root_table,
1);
+#ifdef CONFIG_PROC_FS

        cdrom_root_table->child->de->owner = THIS_MODULE;

+#endif

        /* set the defaults */
        cdrom_sysctl_settings.autoclose = autoclose;

Regards,
Paul Rolland, [email protected]