On Sun, Nov 24, 2013 at 08:07:44AM +0100, Mike Galbraith wrote:
> This patch (commit: 3a72660b07) is only slated for stable 3.12, but
> should go to 3.10/11 as well, no?
Yes, you're right, both 3.10 and 3.11 seem to have the restructuring
patch included (3.10.17 and 3.11.6 respectively), and so should have
this patch also.
> On Wed, 2013-11-20 at 11:44 +0100, Jesper Nilsson wrote:
> > Commit 2caacaa82a51b78fc0c800e206473874094287ed restructured
> > the ipc shm to shorten critical region, but introduced a path
> > where the return value could be -EPERM, even if the operation
> > actually was performed.
> >
> > Before the commit, the err return value was reset by the return value
> > from security_shm_shmctl() after the if (!ns_capable(...)) statement.
> >
> > Now, we still exit the if statement with err set to -EPERM,
> > and in the case of SHM_UNLOCK, it is not reset at all,
> > and used as the return value from shmctl.
> >
> > To fix this, we only set err when errors occur, leaving the
> > fallthrough case alone.
> >
> > Signed-off-by: Jesper Nilsson <jesper.nils...@axis.com>
> > Cc: Andrew Morton <a...@linux-foundation.org>
> > Cc: Davidlohr Bueso <davidl...@hp.com>
> > Cc: Rik van Riel <r...@redhat.com>
> > Cc: Michel Lespinasse <wal...@google.com>
> > Cc: Al Viro <v...@zeniv.linux.org.uk>
> > Cc: stable@vger.kernel.org
> > ---
> > ipc/shm.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/ipc/shm.c b/ipc/shm.c
> > index d697396..4076f9e 100644
> > --- a/ipc/shm.c
> > +++ b/ipc/shm.c
> > @@ -974,12 +974,15 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct
> > shmid_ds __user *, buf)
> > ipc_lock_object(&shp->shm_perm);
> > if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
> > kuid_t euid = current_euid();
> > - err = -EPERM;
> > if (!uid_eq(euid, shp->shm_perm.uid) &&
> > - !uid_eq(euid, shp->shm_perm.cuid))
> > + !uid_eq(euid, shp->shm_perm.cuid)) {
> > + err = -EPERM;
> > goto out_unlock0;
> > - if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
> > + }
> > + if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
> > + err = -EPERM;
> > goto out_unlock0;
> > + }
> > }
> >
> > shm_file = shp->shm_file;
> > --
> > 1.8.4
> >
> >
> > /^JN - Jesper Nilsson
>
>
/^JN - Jesper Nilsson
--
Jesper Nilsson -- jesper.nils...@axis.com
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