Patch "s390: fix handling of -1 in set{,fs}[gu]id16 syscalls" has been added to the 4.9-stable tree

Patch "s390: fix handling of -1 in set{,fs}[gu]id16 syscalls" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     s390-fix-handling-of-1-in-set-fs-id16-syscalls.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6dd0d2d22aa363fec075cb2577ba273ac8462e94 Mon Sep 17 00:00:00 2001
From: Eugene Syromiatnikov <esyr@redhat.com>
Date: Mon, 15 Jan 2018 20:38:17 +0100
Subject: s390: fix handling of -1 in set{,fs}[gu]id16 syscalls

From: Eugene Syromiatnikov <esyr@redhat.com>

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>

---
 arch/s390/kernel/compat_linux.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -110,7 +110,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setregid16,
 
 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,
 
 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,
 
 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)


Patches currently in stable-queue which might be from esyr@redhat.com are

queue-4.9/s390-fix-handling-of-1-in-set-fs-id16-syscalls.patch