commit 5cfe8f1ba5eebe6f4b6e5858cdb1a5be4f3272a6
author Jay Estabrook <jay.estabrook@gmail.com> Sat Nov 16 16:45:31 2013 -0800
committer Matt Turner <mattst88@gmail.com> Sat Nov 16 16:48:42 2013 -0800
tree fd5784acb203c3243c033d9fe6504792d7f1fd0b
parent 6e22f8f2e8d81dcab4c40bc229d53388fda63dbc

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>

arch/alpha/lib/csum_partial_copy.c

diff --git a/arch/alpha/lib/csum_partial_copy.c b/arch/alpha/lib/csum_partial_copy.c
index ffb19b7..ff3c107 100644
--- a/arch/alpha/lib/csum_partial_copy.c
+++ b/arch/alpha/lib/csum_partial_copy.c
@@ -130,7 +130,7 @@
 		*dst = word | tmp;
 		checksum += carry;
 	}
-	if (err) *errp = err;
+	if (err && errp) *errp = err;
 	return checksum;
 }
 
@@ -185,7 +185,7 @@
 		*dst = word | tmp;
 		checksum += carry;
 	}
-	if (err) *errp = err;
+	if (err && errp) *errp = err;
 	return checksum;
 }
 
@@ -242,7 +242,7 @@
 	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 @@
 		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 @@
 
 	if (len) {
 		if (!access_ok(VERIFY_READ, src, len)) {
-			*errp = -EFAULT;
+			if (errp) *errp = -EFAULT;
 			memset(dst, 0, len);
 			return sum;
 		}