linux-kernel - [PATCH] x86: fdiv bug detection fix

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20080731234344.eb3c4ed2.krzysztof.h1@wp.pl>
Date:	Thu, 31 Jul 2008 23:43:44 +0200
From:	Krzysztof Helt <krzysztof.h1@...pl>
To:	hpa@...or.com
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] x86: fdiv bug detection fix

From: Krzysztof Helt <krzysztof.h1@...pl>

The fdiv detection code writes s32 integer into
the boot_cpu_data.fdiv_bug. 
However, the boot_cpu_data.fdiv_bug is only char (s8)
field so the detection overwrites already set fields for
other bugs, e.g. the f00f bug field.

Use local s32 variable to receive result.

Signed-off-by: Krzysztof Helt <krzysztof.h1@...pl>
---

This is a partial fix to Bugzilla #9928  - fixes wrong 
information about the f00f bug (tested) and probably
for coma bug (I have no cpu to test this).

diff -urp linux-alsa/arch/x86/kernel/cpu/bugs.c linux-new/arch/x86/kernel/cpu/bugs.c
--- linux-alsa/arch/x86/kernel/cpu/bugs.c	2008-07-31 12:40:31.000000000 +0200
+++ linux-new/arch/x86/kernel/cpu/bugs.c	2008-07-31 23:24:07.722657435 +0200
@@ -50,6 +50,8 @@ static double __initdata y = 3145727.0;
  */
 static void __init check_fpu(void)
 {
+	s32 fdiv_bug;
+
 	if (!boot_cpu_data.hard_math) {
 #ifndef CONFIG_MATH_EMULATION
 		printk(KERN_EMERG "No coprocessor found and no math emulation present.\n");
@@ -74,8 +76,10 @@ static void __init check_fpu(void)
 		"fistpl %0\n\t"
 		"fwait\n\t"
 		"fninit"
-		: "=m" (*&boot_cpu_data.fdiv_bug)
+		: "=m" (*&fdiv_bug)
 		: "m" (*&x), "m" (*&y));
+
+	boot_cpu_data.fdiv_bug = fdiv_bug;
 	if (boot_cpu_data.fdiv_bug)
 		printk("Hmm, FPU with FDIV bug.\n");
 }
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/