Messages in this thread | | | Date | Wed, 23 Apr 2014 06:58:48 +0200 | From | "Michael Kerrisk (man-pages)" <> | Subject | Re: [PATCH 2/4] ipc/shm.c: check for overflows of shm_tot |
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On 04/21/2014 04:26 PM, Manfred Spraul wrote: > shm_tot counts the total number of pages used by shm segments. > > If SHMALL is ULONG_MAX (or nearly ULONG_MAX), then the number > can overflow. Subsequent calls to shmctl(,SHM_INFO,) would return > wrong values for shm_tot. > > The patch adds a detection for overflows. > > Signed-off-by: Manfred Spraul <manfred@colorfullife.com> > --- > ipc/shm.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/ipc/shm.c b/ipc/shm.c > index 382e2fb..2dfa3d6 100644 > --- a/ipc/shm.c > +++ b/ipc/shm.c > @@ -493,7 +493,8 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) > if (size < SHMMIN || size > ns->shm_ctlmax) > return -EINVAL; > > - if (ns->shm_tot + numpages > ns->shm_ctlall) > + if (ns->shm_tot + numpages < ns->shm_tot || > + ns->shm_tot + numpages > ns->shm_ctlall) > return -ENOSPC; > > shp = ipc_rcu_alloc(sizeof(*shp)); >
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
-- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
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