From: Dmitry V. Levin <ldv@altlinux.org>
Date: Sat, 26 Dec 2015 23:13:27 +0000 (+0300)
Subject: sparc64: fix incorrect sign extension in sys_sparc64_personality
X-Git-Tag: firefly_0821_release~176^2~475^2~257
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a0b1c2d0f53c8368eef4018ed7ce15b6c015aa77;p=firefly-linux-kernel-4.4.55.git

sparc64: fix incorrect sign extension in sys_sparc64_personality

commit 525fd5a94e1be0776fa652df5c687697db508c91 upstream.

The value returned by sys_personality has type "long int".
It is saved to a variable of type "int", which is not a problem
yet because the type of task_struct->pesonality is "unsigned int".
The problem is the sign extension from "int" to "long int"
that happens on return from sys_sparc64_personality.

For example, a userspace call personality((unsigned) -EINVAL) will
result to any subsequent personality call, including absolutely
harmless read-only personality(0xffffffff) call, failing with
errno set to EINVAL.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 30e7ddb27a3a..c690c8e16a96 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -413,7 +413,7 @@ out:
 
 SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
 {
-	int ret;
+	long ret;
 
 	if (personality(current->personality) == PER_LINUX32 &&
 	    personality(personality) == PER_LINUX)