linux-kernel - [PATCH] dmi: Prevent linked list corruption

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Message-ID: <20080211182235.14a5a641@hyperion.delvare>
Date:	Mon, 11 Feb 2008 18:22:35 +0100
From:	Jean Delvare <khali@...ux-fr.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Parag Warudkar <parag.warudkar@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] dmi: Prevent linked list corruption

Adding the same item to a given linked list more than once is guaranteed
to break and corrupt the list. This is however what we do in dmi_scan
since commit 79da4721117fcf188b4b007b775738a530f574da.

Given that there is absolutely no interest in saving empty OEM
strings anyway, I propose the simple and efficient fix below: we
discard the empty OEM strings altogether.

Signed-off-by: Jean Delvare <khali@...ux-fr.org>
Cc: Parag Warudkar <parag.warudkar@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Thomas Gleixner <tglx@...utronix.de>
---
The empty OEM strings weren't even added with the correct entry type
(0 instead of DMI_DEV_TYPE_OEM_STRING.)

 drivers/firmware/dmi_scan.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

--- linux-2.6.25-rc1.orig/drivers/firmware/dmi_scan.c	2008-02-11 16:15:10.000000000 +0100
+++ linux-2.6.25-rc1/drivers/firmware/dmi_scan.c	2008-02-11 18:03:27.000000000 +0100
@@ -217,10 +217,6 @@ static void __init dmi_save_devices(cons
 	}
 }
 
-static struct dmi_device empty_oem_string_dev = {
-	.name = dmi_empty_string,
-};
-
 static void __init dmi_save_oem_strings_devices(const struct dmi_header *dm)
 {
 	int i, count = *(u8 *)(dm + 1);
@@ -229,10 +225,8 @@ static void __init dmi_save_oem_strings_
 	for (i = 1; i <= count; i++) {
 		char *devname = dmi_string(dm, i);
 
-		if (!strcmp(devname, dmi_empty_string)) {
-			list_add(&empty_oem_string_dev.list, &dmi_devices);
+		if (!strcmp(devname, dmi_empty_string))
 			continue;
-		}
 
 		dev = dmi_alloc(sizeof(*dev));
 		if (!dev) {

-- 
Jean Delvare
--
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