linux-kernel - [PATCH] mm, mempolicy: Check parameters first in kernel_get

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Message-Id: <20200801090825.5597-1-haowenchao22@gmail.com>
Date:   Sat,  1 Aug 2020 17:08:26 +0800
From:   Wenchao Hao <haowenchao22@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Wenchao Hao <haowenchao22@...il.com>
Subject: [PATCH] mm, mempolicy: Check parameters first in kernel_get_mempolicy

Previous implement called untagged_addr before error check, while
if the error check failed and return EINVAL, the untagged_addr is
just useless work.

Signed-off-by: Wenchao Hao <haowenchao22@...il.com>
---
 mm/mempolicy.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 381320671677..dac0cd0df3e1 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1632,11 +1632,11 @@ static int kernel_get_mempolicy(int __user *policy,
 	int uninitialized_var(pval);
 	nodemask_t nodes;
 
-	addr = untagged_addr(addr);
-
 	if (nmask != NULL && maxnode < nr_node_ids)
 		return -EINVAL;
 
+	addr = untagged_addr(addr);
+
 	err = do_get_mempolicy(&pval, &nodes, addr, flags);
 
 	if (err)
-- 
2.25.1