Re: [PATCH net v2] ppp: ensure file->private_data can't be overridden

From: Guillaume Nault <redacted>
Date: Mon, 14 Mar 2016 21:17:16 +0100

Locking ppp_mutex must be done before dereferencing file->private_data,
otherwise it could be modified before ppp_unattached_ioctl() takes the
lock. This could lead ppp_unattached_ioctl() to override ->private_data,
thus leaking reference to the ppp_file previously pointed to.

v2: lock all ppp_ioctl() instead of just checking private_data in
    ppp_unattached_ioctl(), to avoid ambiguous behaviour.

Fixes: f3ff8a4d80e8 ("ppp: push BKL down into the driver")
Signed-off-by: Guillaume Nault <redacted>

Applied and queued up for -stable, thanks!