From: H. Peter Anvin <hpa@zytor.com>
Date: Thu, 25 Oct 2007 23:09:38 +0000 (-0700)
Subject: x86 setup: sizeof() is unsigned, unbreak comparisons
X-Git-Tag: v2.6.23.3~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d49e8885782ea938a4d1a2cee4898753e505f70;p=thirdparty%2Fkernel%2Fstable.git

x86 setup: sizeof() is unsigned, unbreak comparisons

patch e6e1ace9904b72478f0c5a5aa7bd174cb6f62561 in mainline.


We use signed values for limit checking since the values can go
negative under certain circumstances.  However, sizeof() is unsigned
and forces the comparison to be unsigned, so move the comparison into
the heap_free() macros so we can ensure it is a signed comparison.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/i386/boot/boot.h b/arch/i386/boot/boot.h
index fb3c40bb02a48..3eeb9e53db9db 100644
--- a/arch/i386/boot/boot.h
+++ b/arch/i386/boot/boot.h
@@ -216,9 +216,9 @@ static inline char *__get_heap(size_t s, size_t a, size_t n)
 #define GET_HEAP(type, n) \
 	((type *)__get_heap(sizeof(type),__alignof__(type),(n)))
 
-static inline int heap_free(void)
+static inline bool heap_free(size_t n)
 {
-	return heap_end-HEAP;
+	return (int)(heap_end-HEAP) >= (int)n;
 }
 
 /* copy.S */
diff --git a/arch/i386/boot/video-bios.c b/arch/i386/boot/video-bios.c
index 68e65d95cdfd8..ed0672a818709 100644
--- a/arch/i386/boot/video-bios.c
+++ b/arch/i386/boot/video-bios.c
@@ -79,7 +79,7 @@ static int bios_probe(void)
 	video_bios.modes = GET_HEAP(struct mode_info, 0);
 
 	for (mode = 0x14; mode <= 0x7f; mode++) {
-		if (heap_free() < sizeof(struct mode_info))
+		if (!heap_free(sizeof(struct mode_info)))
 			break;
 
 		if (mode_defined(VIDEO_FIRST_BIOS+mode))
diff --git a/arch/i386/boot/video-vesa.c b/arch/i386/boot/video-vesa.c
index 1921907107102..4716b9a963575 100644
--- a/arch/i386/boot/video-vesa.c
+++ b/arch/i386/boot/video-vesa.c
@@ -57,7 +57,7 @@ static int vesa_probe(void)
 	while ((mode = rdfs16(mode_ptr)) != 0xffff) {
 		mode_ptr += 2;
 
-		if (heap_free() < sizeof(struct mode_info))
+		if (!heap_free(sizeof(struct mode_info)))
 			break;	/* Heap full, can't save mode info */
 
 		if (mode & ~0x1ff)
diff --git a/arch/i386/boot/video.c b/arch/i386/boot/video.c
index e4ba897bf9a37..ad9712f017397 100644
--- a/arch/i386/boot/video.c
+++ b/arch/i386/boot/video.c
@@ -371,7 +371,7 @@ static void save_screen(void)
 	saved.curx = boot_params.screen_info.orig_x;
 	saved.cury = boot_params.screen_info.orig_y;
 
-	if (heap_free() < saved.x*saved.y*sizeof(u16)+512)
+	if (!heap_free(saved.x*saved.y*sizeof(u16)+512))
 		return;		/* Not enough heap to save the screen */
 
 	saved.data = GET_HEAP(u16, saved.x*saved.y);