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    Subject[PATCH 3.19.y-ckt 147/196] do_last(): don't let a bogus return value from ->open() et.al. to confuse us
    Date
    3.19.8-ckt16 -stable review patch.  If anyone has any objections, please let me know.

    ---8<------------------------------------------------------------

    From: Al Viro <viro@zeniv.linux.org.uk>

    commit c80567c82ae4814a41287618e315a60ecf513be6 upstream.

    ... into returning a positive to path_openat(), which would interpret that
    as "symlink had been encountered" and proceed to corrupt memory, etc.
    It can only happen due to a bug in some ->open() instance or in some LSM
    hook, etc., so we report any such event *and* make sure it doesn't trick
    us into further unpleasantness.

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    fs/namei.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/fs/namei.c b/fs/namei.c
    index f38cb09..6c363c9 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -3124,6 +3124,10 @@ opened:
    goto exit_fput;
    }
    out:
    + if (unlikely(error > 0)) {
    + WARN_ON(1);
    + error = -EINVAL;
    + }
    if (got_write)
    mnt_drop_write(nd->path.mnt);
    path_put(&save_parent);
    --
    2.7.0
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