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>
diff --git a/ipc/shm.c b/ipc/shm.c
index dda8f1f..9e51bf2 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -493,7 +493,8 @@
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));