linux-kernel - [PATCH 3/4] ipc/shm.c: check for integer overflow during shmget.

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Message-Id: <1398090397-2397-4-git-send-email-manfred@colorfullife.com>
Date:	Mon, 21 Apr 2014 16:26:36 +0200
From:	Manfred Spraul <manfred@...orfullife.com>
To:	Davidlohr Bueso <davidlohr.bueso@...com>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	gthelen@...gle.com, aswin@...com, linux-mm@...ck.org,
	Manfred Spraul <manfred@...orfullife.com>
Subject: [PATCH 3/4] ipc/shm.c: check for integer overflow during shmget.

SHMMAX is the upper limit for the size of a shared memory segment,
counted in bytes. The actual allocation is that size, rounded up to
the next full page.
Add a check that prevents the creation of segments where the
rounded up size causes an integer overflow.

Signed-off-by: Manfred Spraul <manfred@...orfullife.com>
---
 ipc/shm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/ipc/shm.c b/ipc/shm.c
index 2dfa3d6..f000696 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -493,6 +493,9 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 	if (size < SHMMIN || size > ns->shm_ctlmax)
 		return -EINVAL;
 
+	if (numpages << PAGE_SHIFT < size)
+		return -ENOSPC;
+
 	if (ns->shm_tot + numpages < ns->shm_tot ||
 			ns->shm_tot + numpages > ns->shm_ctlall)
 		return -ENOSPC;
-- 
1.9.0

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