[Xen-devel] [PATCH] linux: range-check hypercall index in privcmd

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

Otherwise, bugs in e.g. libxc may bring the kernel down.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: head-2006-10-16/drivers/xen/privcmd/privcmd.c
===================================================================
--- head-2006-10-16.orig/drivers/xen/privcmd/privcmd.c  2006-10-24 
15:17:49.000000000 +0200
+++ head-2006-10-16/drivers/xen/privcmd/privcmd.c       2006-10-24 
15:19:40.000000000 +0200
@@ -53,6 +53,8 @@ static int privcmd_ioctl(struct inode *i
                        return -EFAULT;
 
 #if defined(__i386__)
+               if (hypercall.op >= (PAGE_SIZE >> 5))
+                       break;
                __asm__ __volatile__ (
                        "pushl %%ebx; pushl %%ecx; pushl %%edx; "
                        "pushl %%esi; pushl %%edi; "
@@ -69,21 +71,21 @@ static int privcmd_ioctl(struct inode *i
                        "popl %%ecx; popl %%ebx"
                        : "=a" (ret) : "0" (&hypercall) : "memory" );
 #elif defined (__x86_64__)
-               {
+               if (hypercall.op < (PAGE_SIZE >> 5)) {
                        long ign1, ign2, ign3;
                        __asm__ __volatile__ (
                                "movq %8,%%r10; movq %9,%%r8;"
-                               "shlq $5,%%rax ;"
+                               "shll $5,%%eax ;"
                                "addq $hypercall_page,%%rax ;"
                                "call *%%rax"
                                : "=a" (ret), "=D" (ign1),
                                  "=S" (ign2), "=d" (ign3)
-                               : "0" ((unsigned long)hypercall.op), 
-                               "1" ((unsigned long)hypercall.arg[0]), 
-                               "2" ((unsigned long)hypercall.arg[1]),
-                               "3" ((unsigned long)hypercall.arg[2]), 
-                               "g" ((unsigned long)hypercall.arg[3]),
-                               "g" ((unsigned long)hypercall.arg[4])
+                               : "0" ((unsigned int)hypercall.op),
+                               "1" (hypercall.arg[0]),
+                               "2" (hypercall.arg[1]),
+                               "3" (hypercall.arg[2]),
+                               "g" (hypercall.arg[3]),
+                               "g" (hypercall.arg[4])
                                : "r8", "r10", "memory" );
                }
 #elif defined (__ia64__)


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