From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Wed, 31 Jan 2018 10:35:52 +0000 (+0000)
Subject: xen/cmdline: Fix parse_boolean() for unadorned values
X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~661
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=ac37ec1ddef234eeba6f438c29ff687c64962ebd;p=xen.git

xen/cmdline: Fix parse_boolean() for unadorned values

A command line such as "cpuid=no-ibrsb,no-stibp" tickles a bug in
parse_boolean() because the separating comma fails the NUL case.

Instead, check for slen == nlen which accounts for the boundary (if any)
passed via the 'e' parameter.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---

diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 19f9bad48d..5766a0f784 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -259,12 +259,16 @@ int parse_boolean(const char *name, const char *s, const char *e)
     if ( slen < nlen || strncmp(s, name, nlen) )
         return -1;
 
-    switch ( s[nlen] )
-    {
-    case '\0': return val;
-    case '=':  return parse_bool(&s[nlen + 1], e);
-    default:   return -1;
-    }
+    /* Exact, unadorned name?  Result depends on the 'no-' prefix. */
+    if ( slen == nlen )
+        return val;
+
+    /* =$SOMETHING?  Defer to the regular boolean parsing. */
+    if ( s[nlen] == '=' )
+        return parse_bool(&s[nlen + 1], e);
+
+    /* Unrecognised.  Give up. */
+    return -1;
 }
 
 unsigned int tainted;