linux-kernel - [patch 2/2 v2] staging: lustre: integer overflow in obd_ioctl_is

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Message-ID: <20140428105858.GA31925@mwanda>
Date:	Mon, 28 Apr 2014 13:58:58 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Peng Tao <bergwolf@...il.com>,
	Andreas Dilger <andreas.dilger@...el.com>,
	Oleg Drokin <oleg.drokin@...el.com>,
	"John L. Hammond" <john.hammond@...el.com>,
	Dmitry Eremin <dmitry.eremin@...el.com>,
	Jinshan Xiong <jinshan.xiong@...el.com>,
	Dulshani Gunawardhana <dulshani.gunawardhana89@...il.com>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org, walter harms <wharms@....de>
Subject: [patch 2/2 v2] staging: lustre: integer overflow in
 obd_ioctl_is_invalid()

The obd_ioctl_getdata() function caps "data->ioc_len" at
OBD_MAX_IOCTL_BUFFER and then calls this obd_ioctl_is_invalid() to check
that the other values inside data are valid.

There are several lengths inside data but when they are added together
they must not be larger than "data->ioc_len".  The checks against
"(data->ioc_inllen1 > (1<<30))" are supposed to ensure that the addition
does not have an integer overflow.  But "(1<<30) * 4" actually can
overflow 32 bits, so the checks are insufficient.

I have changed it to "> OBD_MAX_IOCTL_BUFFER" instead.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
v2: Updated the error messages as Walter Harms pointed out.

diff --git a/drivers/staging/lustre/lustre/include/lustre_lib.h b/drivers/staging/lustre/lustre/include/lustre_lib.h
index bdc9812..3c26bbd 100644
--- a/drivers/staging/lustre/lustre/include/lustre_lib.h
+++ b/drivers/staging/lustre/lustre/include/lustre_lib.h
@@ -179,24 +179,25 @@ static inline int obd_ioctl_packlen(struct obd_ioctl_data *data)
 
 static inline int obd_ioctl_is_invalid(struct obd_ioctl_data *data)
 {
-	if (data->ioc_len > (1<<30)) {
-		CERROR("OBD ioctl: ioc_len larger than 1<<30\n");
+	if (data->ioc_len > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_len larger than %d\n",
+		       OBD_MAX_IOCTL_BUFFER);
 		return 1;
 	}
-	if (data->ioc_inllen1 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen1 larger than 1<<30\n");
+	if (data->ioc_inllen1 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen1 larger than ioc_len\n");
 		return 1;
 	}
-	if (data->ioc_inllen2 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen2 larger than 1<<30\n");
+	if (data->ioc_inllen2 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen2 larger than ioc_len\n");
 		return 1;
 	}
-	if (data->ioc_inllen3 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen3 larger than 1<<30\n");
+	if (data->ioc_inllen3 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen3 larger than ioc_len\n");
 		return 1;
 	}
-	if (data->ioc_inllen4 > (1<<30)) {
-		CERROR("OBD ioctl: ioc_inllen4 larger than 1<<30\n");
+	if (data->ioc_inllen4 > OBD_MAX_IOCTL_BUFFER) {
+		CERROR("OBD ioctl: ioc_inllen4 larger than ioc_len\n");
 		return 1;
 	}
 	if (data->ioc_inlbuf1 && !data->ioc_inllen1) {
--
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