Commit 09c6eb1f authored Jun 06, 2014 by Manfred Spraul Committed by Linus Torvalds Jun 06, 2014

ipc/shm.c: check for overflows of shm_tot



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>
Acked-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 247a8ce8

ipc/shm.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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));

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