[LU-4787] OOPS from null pointer dereference in mdc_unpack_acl

• Type: Bug
• Resolution: Duplicate
• Priority: Major
• Fix Version/s: Lustre 2.6.0
• Affects Version/s: Lustre 2.6.0, Lustre 2.5.1, Lustre 2.4.3
• Environment: ZFS based 2.5.1 MGS/MDS/OSS + 2.5.1 or in-kernel client
• Severity: 3
• Assignee: WC Triage
• Reporter: Roland Fehrenbacher

Description

A kernel oops is generated when body->aclsize != 0 in mdc_unpack_acl, but posix_acl_from_xattr
returns a null pointer. The pointer is checked for error codes, but not for a null value.
The cause of the problem is most likely some data corruption on the MDT side, but the client should tolerate this by sending an error.

Issue Links

• is related to: LU-5150 NULL pointer dereference in posix_acl_valid() under mdc_get_lustre_md()

Comments

[Roland Fehrenbacher]

Andreas, no hard feelings about this here Just added LU-5840 to discuss the issue
further along the lines mentioned in LU-5150.

[Andreas Dilger]

Roland, apologies that we didn't see the patch here. I agree it would have been better to see and land it before more people hit the bug, but at least it was fixed in 2.6, and is scheduled to land for 2.5.4 also.

Thanks for bringing the missing patch back to our attention.

[Roland Fehrenbacher]

The attached patch fixes the issue and can be applied
to master, b2_5 and b2_4 as well as the in-kernel client.