From: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Date: Thu, 6 Jun 2019 12:08:10 +0000 (+0200)
Subject: bitmap: fix bitmap_fill with zero-sized bitmap
X-Git-Tag: RELEASE-4.11.2~32
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=ba75e0d44b58c53696c09eaea7fc53c923c3ccc5;p=people%2Fdwmw2%2Fxen.git

bitmap: fix bitmap_fill with zero-sized bitmap

When bitmap_fill(..., 0) is called, do not try to write anything. Before
this patch, it tried to write almost LONG_MAX, surely overwriting
something.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 93df28be2d4f620caf18109222d046355ac56327
master date: 2019-05-13 10:12:00 +0200
---

diff --git a/xen/include/xen/bitmap.h b/xen/include/xen/bitmap.h
index e2a368691e..ab3b113fd1 100644
--- a/xen/include/xen/bitmap.h
+++ b/xen/include/xen/bitmap.h
@@ -132,6 +132,8 @@ static inline void bitmap_fill(unsigned long *dst, int nbits)
 	size_t nlongs = BITS_TO_LONGS(nbits);
 
 	switch (nlongs) {
+	case 0:
+		break;
 	default:
 		memset(dst, -1, (nlongs - 1) * sizeof(unsigned long));
 		/* fall through */