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    SubjectRe: [34-longterm 238/247] xfs: prevent leaking uninitialized stack memory in FSGEOMETRY_V1
    From
    On Thu, Jun 23, 2011 at 1:49 PM, Dan Rosenberg <drosenberg@vsecurity.com> wrote:
    > On Thu, 2011-06-23 at 13:35 -0400, Paul Gortmaker wrote:
    >> From: Dan Rosenberg <drosenberg@vsecurity.com>
    >>
    >>                    -------------------
    >>     This is a commit scheduled for the next v2.6.34 longterm release.
    >>     If you see a problem with using this for longterm, please comment.
    >>                    -------------------
    >>
    >> commit 3a3675b7f23f83ca8c67c9c2b6edf707fd28d1ba 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.
    >>
    >> v2 switches to memset() to avoid future issues if structure members
    >> change, on suggestion of Dave Chinner.
    >>
    >> Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
    >> Reviewed-by: Eugene Teo <eugeneteo@kernel.org>
    >> Signed-off-by: Alex Elder <aelder@sgi.com>
    >> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    >> ---
    >>  fs/xfs/xfs_fsops.c |    3 +++
    >>  1 files changed, 3 insertions(+), 0 deletions(-)
    >>
    >> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
    >> index 37a6f62..4e7f02b 100644
    >> --- a/fs/xfs/xfs_fsops.c
    >> +++ b/fs/xfs/xfs_fsops.c
    >> @@ -57,6 +57,9 @@ xfs_fs_geometry(
    >>       xfs_fsop_geom_t         *geo,
    >>       int                     new_version)
    >>  {
    >> +
    >> +     memset(geo, 0, sizeof(*geo));
    >> +
    >>       geo->blocksize = mp->m_sb.sb_blocksize;
    >>       geo->rtextsize = mp->m_sb.sb_rextsize;
    >>       geo->agblocks = mp->m_sb.sb_agblocks;
    >> --
    >> 1.7.4.4
    >
    > This introduced a regression which was fixed by commit
    > af24ee9ea8d532e16883251a6684dfa1be8eec29.

    Thanks Dan,

    Fix queued and will appear shortly here.

    http://git.kernel.org/?p=linux/kernel/git/longterm/longterm-queue-2.6.34.git;a=summary

    Paul.

    >
    > -Dan
    >
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