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

From: Manfred Spraul
Date: Sat Apr 19 2014 - 07:44:59 EST


SHMMAX is the upper limit 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@xxxxxxxxxxxxxxxx>
---
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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