xfs: zero proper structure size for geometry calls
commit277678c4089dc0a9b3235eb58547878dacfe336b
authorAlex Elder <aelder@sgi.com>
Tue, 1 Mar 2011 17:50:00 +0000 (1 17:50 +0000)
committerGreg Kroah-Hartman <gregkh@suse.de>
Thu, 14 Apr 2011 23:53:16 +0000 (14 16:53 -0700)
tree4241a921318323cb4ce948006a251385c13592bf
parentb291661643c93044e6d4a228d3268649ccf30a0c
xfs: zero proper structure size for geometry calls

commit af24ee9ea8d532e16883251a6684dfa1be8eec29 upstream.

Commit 493f3358cb289ccf716c5a14fa5bb52ab75943e5 added this call to
xfs_fs_geometry() in order to avoid passing kernel stack data back
to user space:

+       memset(geo, 0, sizeof(*geo));

Unfortunately, one of the callers of that function passes the
address of a smaller data type, cast to fit the type that
xfs_fs_geometry() requires.  As a result, this can happen:

Kernel panic - not syncing: stack-protector: Kernel stack is corrupted
in: f87aca93

Pid: 262, comm: xfs_fsr Not tainted 2.6.38-rc6-493f3358cb2+ #1
Call Trace:

[<c12991ac>] ? panic+0x50/0x150
[<c102ed71>] ? __stack_chk_fail+0x10/0x18
[<f87aca93>] ? xfs_ioc_fsgeometry_v1+0x56/0x5d [xfs]

Fix this by fixing that one caller to pass the right type and then
copy out the subset it is interested in.

Note: This patch is an alternative to one originally proposed by
Eric Sandeen.

Reported-by: Jeffrey Hundstad <jeffrey.hundstad@mnsu.edu>
Signed-off-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Tested-by: Jeffrey Hundstad <jeffrey.hundstad@mnsu.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
fs/xfs/linux-2.6/xfs_ioctl.c