Re: [Stable-review] [18/74] xfs: prevent leaking uninitializedstack memory in FSGEOMETRY_V1

[Ben Hutchings]

On Wed, 2011-04-13 at 08:50 -0700, Greg KH wrote:
> 2.6.32-longterm review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> 
> From: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
> 
> commit c4d0c3b097f7584772316ee4d64a09fe0e4ddfca upstream.
> 
> The FSGEOMETRY_V1 ioctl (and its compat equivalent) calls out to
> xfs_fs_geometry() with a version number of 3.  This code path does not
> fill in the logsunit member of the passed xfs_fsop_geom_t, leading to
> the leaking of four bytes of uninitialized stack data to potentially
> unprivileged callers.
[...]

This caused a serious regression and requires a second fix:

commit af24ee9ea8d532e16883251a6684dfa1be8eec29
Author: Alex Elder <aelder@xxxxxxx>
Date:   Tue Mar 1 17:50:00 2011 +0000

    xfs: zero proper structure size for geometry calls

Ben.

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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