alpha: Prevent a NULL ptr dereference in csum_partial_copy.

Introduced by 3ddc5b46a8e90f3c92 ("kernel-wide: fix missing validations
on __get/__put/__copy_to/__copy_from_user()").

Also fix some other places which could be problematic in a similar way,
although they hadn't been proved so, as far as I can tell.

Cc: Michael Cree <mcree@orcon.net.nz>
Signed-off-by: Matt Turner <mattst88@gmail.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/arch/alpha/lib/csum_partial_copy.c b/arch/alpha/lib/csum_partial_copy.c
index ffb19b7da999..ff3c10721caf 100644
--- a/arch/alpha/lib/csum_partial_copy.c
+++ b/arch/alpha/lib/csum_partial_copy.c
@@ -130,7 +130,7 @@ csum_partial_cfu_aligned(const unsigned long __user *src, unsigned long *dst,
                 *dst = word | tmp;
                 checksum += carry;
         }
-        if (err) *errp = err;
+        if (err && errp) *errp = err;
         return checksum;
 }
 
@@ -185,7 +185,7 @@ csum_partial_cfu_dest_aligned(const unsigned long __user *src,
                 *dst = word | tmp;
                 checksum += carry;
         }
-        if (err) *errp = err;
+        if (err && errp) *errp = err;
         return checksum;
 }
 
@@ -242,7 +242,7 @@ csum_partial_cfu_src_aligned(const unsigned long __user *src,
         stq_u(partial_dest | second_dest, dst);
 out:
         checksum += carry;
-        if (err) *errp = err;
+        if (err && errp) *errp = err;
         return checksum;
 }
 
@@ -325,7 +325,7 @@ csum_partial_cfu_unaligned(const unsigned long __user * src,
                 stq_u(partial_dest | word | second_dest, dst);
                 checksum += carry;
         }
-        if (err) *errp = err;
+        if (err && errp) *errp = err;
         return checksum;
 }
 
@@ -339,7 +339,7 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 
         if (len) {
                 if (!access_ok(VERIFY_READ, src, len)) {
-                        *errp = -EFAULT;
+                        if (errp) *errp = -EFAULT;
                         memset(dst, 0, len);
                         return sum;
                 }