s390: fix handling of -1 in set{,fs}[gu]id16 syscalls

commit 6dd0d2d22aa363fec075cb2577ba273ac8462e94 upstream.

For some reason, the implementation of some 16-bit ID system calls
(namely, setuid16/setgid16 and setfsuid16/setfsgid16) used type cast
instead of low2highgid/low2highuid macros for converting [GU]IDs, which
led to incorrect handling of value of -1 (which ought to be considered
invalid).

Discovered by strace test suite.

Cc: stable@vger.kernel.org
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 59eea9c65d3e9e8595d509001b1c794420060887..79b7a3438d549e20fa8b5f770a21319465256b64 100644 (file)
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -110,7 +110,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setregid16, u16, rgid, u16, egid)
 
 COMPAT_SYSCALL_DEFINE1(s390_setgid16, u16, gid)
 {
-       return sys_setgid((gid_t)gid);
+       return sys_setgid(low2highgid(gid));
 }
 
 COMPAT_SYSCALL_DEFINE2(s390_setreuid16, u16, ruid, u16, euid)
@@ -120,7 +120,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setreuid16, u16, ruid, u16, euid)
 
 COMPAT_SYSCALL_DEFINE1(s390_setuid16, u16, uid)
 {
-       return sys_setuid((uid_t)uid);
+       return sys_setuid(low2highuid(uid));
 }
 
 COMPAT_SYSCALL_DEFINE3(s390_setresuid16, u16, ruid, u16, euid, u16, suid)
@@ -173,12 +173,12 @@ COMPAT_SYSCALL_DEFINE3(s390_getresgid16, u16 __user *, rgidp,
 
 COMPAT_SYSCALL_DEFINE1(s390_setfsuid16, u16, uid)
 {
-       return sys_setfsuid((uid_t)uid);
+       return sys_setfsuid(low2highuid(uid));
 }
 
 COMPAT_SYSCALL_DEFINE1(s390_setfsgid16, u16, gid)
 {
-       return sys_setfsgid((gid_t)gid);
+       return sys_setfsgid(low2highgid(gid));
 }
 
 static int groups16_to_user(u16 __user *grouplist, struct group_info *group_info)