MIPS: compat: Don't clobber personality bits in 32-bit sys_personality().

If PER_LINUX32 has been set on a 32-bit kernel, only twiddle with the
low-order personality bits, let the upper bits pass through.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Cc: Camm Maguire <camm@maguirefamily.org>
Patchwork: https://patchwork.linux-mips.org/patch/1751/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 6343b4a5b835..876a75cc376f 100644
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -251,14 +251,15 @@ SYSCALL_DEFINE5(n32_msgrcv, int, msqid, u32, msgp, size_t, msgsz,
 
 SYSCALL_DEFINE1(32_personality, unsigned long, personality)
 {
+        unsigned int p = personality & 0xffffffff;
         int ret;
-        personality &= 0xffffffff;
+
         if (personality(current->personality) == PER_LINUX32 &&
-            personality == PER_LINUX)
-                personality = PER_LINUX32;
-        ret = sys_personality(personality);
-        if (ret == PER_LINUX32)
-                ret = PER_LINUX;
+            personality(p) == PER_LINUX)
+                p = (p & ~PER_MASK) | PER_LINUX32;
+        ret = sys_personality(p);
+        if (ret != -1 && personality(ret) == PER_LINUX32)
+                ret = (ret & ~PER_MASK) | PER_LINUX;
         return ret;
 }