Bug 11952 - 33.8 (65535/16/63) IDE large drive bug
33.8 (65535/16/63) IDE large drive bug
Product: Red Hat Linux
Classification: Retired
Component: kernel (Show other bugs)
i386 Linux
medium Severity high
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Assigned To: Michael K. Johnson
Depends On:
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Reported: 2000-06-07 11:05 EDT by Richard Rudell
Modified: 2008-05-01 11:37 EDT (History)
0 users

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Doc Type: Bug Fix
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Last Closed: 2000-06-07 11:05:51 EDT
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Description Richard Rudell 2000-06-07 11:05:50 EDT
Attempting to install a 40 GB Maxtor drive.

Symptom: fdisk drive as one partition; correctly says 4982/255/63 for 
C/H/S.  Make an ext2 filesystem which appears to succeed.  Mount the 
filesystem -- get errors.  fsck the filesystem and see that block 517 is 
in two free lists at sectors 2 and 4120706.

Note that the delta between these is very close to 65535/16/63, indicating 
a 33.8GB bug.

This is a bug in the kernel drivers/block/ide-disk.c where a short 
overflows when attempting to compute the cyc value based on the bios 
values of 16/63 (and not the artifical values of 255/63).  This leads to 
attempts to write sector >= 66059280 (65535*16*63) to actually cause a 
write to the sector modulo this value leading to serious data corruption.

THIS IS FIXED IN 2.2.14 (RedHat 6.2) and presumably thereafter, although 
the version number of ide-disk.c didn't change (1.08)

The bug is present in 2.2.12 (RedHat 6.1).  Anyone attempting to use large 
ide drives should upgrade to RH 6.2.

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