From: Luis Felipe Sandoval Castro <luis.felipe.sandoval.castro@intel.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Luis Felipe Sandoval Castro <luis.felipe.sandoval.castro@intel.com>
Subject: [PATCH v1] mm/mempolicy.c: Fix get_nodes() off-by-one error.
Date: Tue, 18 Jul 2017 08:39:24 -0500 [thread overview]
Message-ID: <1500385164-11062-1-git-send-email-luis.felipe.sandoval.castro@intel.com> (raw)
set_mempolicy() and mbind() take as argument a pointer to a bit mask
(nodemask) and the number of bits in the mask the kernel will use
(maxnode), among others. For instace on a system with 2 NUMA nodes valid
masks are: 0b00, 0b01, 0b10 and 0b11 it's clear maxnode=2, however an
off-by-one error in get_nodes() the function that copies the node mask from
user space requires users to pass maxnode = 3 in this example and maxnode =
actual_maxnode + 1 in the general case. This patch fixes such error.
Signed-off-by: Luis Felipe Sandoval Castro <luis.felipe.sandoval.castro@intel.com>
---
mm/mempolicy.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d911fa5..5274e9d2 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1208,11 +1208,10 @@ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
unsigned long nlongs;
unsigned long endmask;
- --maxnode;
nodes_clear(*nodes);
- if (maxnode == 0 || !nmask)
+ if (maxnode == 1 || !nmask)
return 0;
- if (maxnode > PAGE_SIZE*BITS_PER_BYTE)
+ if (maxnode - 1 > PAGE_SIZE * BITS_PER_BYTE)
return -EINVAL;
nlongs = BITS_TO_LONGS(maxnode);
--
1.8.3.1
--
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next reply other threads:[~2017-07-18 21:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-18 13:39 Luis Felipe Sandoval Castro [this message]
2017-10-06 13:36 [PATCH v1][cover-letter] mm/mempolicy.c: Fix get_nodes() off-by-one error Luis Felipe Sandoval Castro
2017-10-06 13:36 ` [PATCH v1] " Luis Felipe Sandoval Castro
2017-10-12 8:46 ` Michal Hocko
2017-10-12 9:14 ` Vlastimil Babka
2017-10-12 9:29 ` Michal Hocko
2017-10-12 15:28 ` Andi Kleen
2017-10-13 8:04 ` Michal Hocko
2017-10-19 3:48 ` Sandoval Castro, Luis Felipe
2017-10-19 4:28 ` Andi Kleen
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