Re: Oops in 2.1.131 accessing IDE CD-ROM

Guest section DW (dwguest@win.tue.nl)
Sat, 5 Dec 1998 18:30:04 +0100 (MET)

The real problem may be entirely different, but at least
there is a flaw in the isofs code there, where the result
of get_blkfops() is dereferenced without testing for NULL.
So, a slightly healthier version may be

--- inode.c~ Sat Sep 26 01:27:13 1998
+++ inode.c Sat Dec 5 18:23:14 1998
@@ -409,11 +409,13 @@
struct cdrom_multisession ms_info;
unsigned int vol_desc_start;
struct inode inode_fake;
+ struct file_operations *fops;
extern struct file_operations * get_blkfops(unsigned int);
int i;

vol_desc_start=0;
- if (get_blkfops(MAJOR(dev))->ioctl!=NULL)
+ fops = get_blkfops(MAJOR(dev));
+ if (fops && fops->ioctl)
{
/* Whoops. We must save the old FS, since otherwise
* we would destroy the kernels idea about FS on root
@@ -423,10 +425,8 @@
inode_fake.i_rdev=dev;
ms_info.addr_format=CDROM_LBA;
set_fs(KERNEL_DS);
- i=get_blkfops(MAJOR(dev))->ioctl(&inode_fake,
- NULL,
- CDROMMULTISESSION,
- (unsigned long) &ms_info);
+ i = fops->ioctl(&inode_fake, NULL, CDROMMULTISESSION,
+ (unsigned long) &ms_info);
set_fs(old_fs);
#if 0
printk("isofs.inode: CDROMMULTISESSION: rc=%d\n",i);

-
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