IJ50372: TRUNCATION OCCURS DURING ATOMIC_OPEN() CODE PATH

APAR status

• Closed as program error.

Error description

• O_TRUNC is not ignored correctly after a successful file lookup
  during atomic_open() so truncation can happen during the open
  routine, before permission checks happen. This leads to a
  scenario in which a user on a different node can truncate a file
  which he does not have permissions to.
  

Local fix

• - Avoid using O_TRUNC with atomic_open()
  

Problem summary

• O_TRUNC is not ignored correctly after a successful file lookup
  during atomic_open() so truncation can happen during the open
  routine, before permission checks happen. This leads to a
  scenario in which a user on a different node can truncate a file
  which he does not have permissions to.
  

Problem conclusion

• This problem is fixed in 5.1.9.3
  To see all Spectrum Scale APARs and their respective
  Fix solutions refer to page:
  https://public.dhe.ibm.com/storage/spectrumscale/spectrum_scale_
  apars.html
  
  Benefits of the solution:
  Fixed the code so O_TRUNC is correctly ignored during open. The
  truncation will be performed after permission checks.
  
  Work Around:
  - Avoid using O_TRUNC with atomic_open()
  
  Problem trigger:
  - A file is created under a user
  with no write permissions for group and others (e.g mode 644) in
  one node
  - A user on a different node atomic opens the file with O_TRUNC
  flag and tries to write to it
  
  Symptom:
  Unexpected Results/Behavior   
  
  Platforms affected:
  All Linux OS environments
  
  Functional Area affected:
  All Scale Users
  
  Customer Impact:
  Critical
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  SPEC SCALE STD

• Fixed component ID

  5737F33AP

Applicable component levels