linux-kernel - [PATCH] powerpc/mm: Return directly after a failed __copy_from_user() in sys_subpage

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Date:   Sat, 21 Jan 2017 16:24:58 +0100
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     linuxppc-dev@...ts.ozlabs.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] powerpc/mm: Return directly after a failed __copy_from_user()
 in sys_subpage_prot()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Sat, 21 Jan 2017 16:10:50 +0100

* Return directly after a call of the function "__copy_from_user"
  failed here.

  This issue was detected by using the Coccinelle software.

* Delete the jump label "out2" which became unnecessary with
  this refactoring.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 arch/powerpc/mm/subpage-prot.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
index d5543514c1df..40309edd7cb7 100644
--- a/arch/powerpc/mm/subpage-prot.c
+++ b/arch/powerpc/mm/subpage-prot.c
@@ -248,9 +248,8 @@ long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
 			nw = (next - addr) >> PAGE_SHIFT;
 
 		up_write(&mm->mmap_sem);
-		err = -EFAULT;
 		if (__copy_from_user(spp, map, nw * sizeof(u32)))
-			goto out2;
+			return -EFAULT;
 		map += nw;
 		down_write(&mm->mmap_sem);
 
@@ -262,6 +261,5 @@ long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
 	err = 0;
  out:
 	up_write(&mm->mmap_sem);
- out2:
 	return err;
 }
-- 
2.11.0