sparc64: fix incorrect sign extension in sys_sparc64_personality
authorDmitry V. Levin <ldv@altlinux.org>
Sat, 26 Dec 2015 23:13:27 +0000 (02:13 +0300)
committerBen Hutchings <ben@decadent.org.uk>
Sat, 13 Feb 2016 10:34:09 +0000 (10:34 +0000)
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: Ben Hutchings <ben@decadent.org.uk>
arch/sparc/kernel/sys_sparc_64.c

index 0ff682d..a062fe9 100644 (file)
@@ -517,7 +517,7 @@ out:
 
 SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
 {
 
 SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
 {
-       int ret;
+       long ret;
 
        if (personality(current->personality) == PER_LINUX32 &&
            personality(personality) == PER_LINUX)
 
        if (personality(current->personality) == PER_LINUX32 &&
            personality(personality) == PER_LINUX)