All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dan Carpenter <dan.carpenter@oracle.com>
To: GOTO Masanori <gotom@debian.or.jp>
Cc: YOKOTA Hiroshi <yokota@netlab.is.tsukuba.ac.jp>,
	"James E.J. Bottomley" <JBottomley@parallels.com>,
	linux-scsi@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [patch] [SCSI] nsp32: fix an off by one
Date: Thu, 03 Apr 2014 07:28:53 +0000	[thread overview]
Message-ID: <20140403072853.GC14286@mwanda> (raw)

This off by one bug will cause memory corruption when we use every
sglun.

The problem is that NSP32_SG_TABLE_SIZE is too small.  Here is how
it's caculated in the original code:

	sizeof(nsp32_sgtable) * NSP32_SG_SIZE * MAX_TARGET * MAX_LUN

But the problem is that the NSP32_SG_SIZE should be (NSP32_SG_SIZE + 1)
like this:

	sizeof(nsp32_sgtable) * (NSP32_SG_SIZE + 1) * MAX_TARGET * MAX_LUN

Or another more intuitive way to write it would be:

	sizeof(nsp32_sglun) * MAX_TARGET * MAX_LUN

We use NSP32_SG_TABLE_SIZE to allocate data->sg_list which is an array
of nsp32_sglun structs.  The array has MAX_TARGET * MAX_LUN elements.

MAX_TARGET (8) * MAX_LUN (8) = 64 elements.  The missing "+ 1" means
that we only allocate enough space for 63 elements.  In terms of bytes,
the old code allocated 65536 bytes and now it allocates 66048 bytes.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
Static checker stuff.

diff --git a/drivers/scsi/nsp32.h b/drivers/scsi/nsp32.h
index c022182..d94f4cd 100644
--- a/drivers/scsi/nsp32.h
+++ b/drivers/scsi/nsp32.h
@@ -454,7 +454,7 @@ typedef struct _nsp32_sgtable {
 typedef struct _nsp32_sglun {
 	nsp32_sgtable sgt[NSP32_SG_SIZE+1];	/* SG table */
 } __attribute__ ((packed)) nsp32_sglun;
-#define NSP32_SG_TABLE_SIZE (sizeof(nsp32_sgtable) * NSP32_SG_SIZE * MAX_TARGET * MAX_LUN)
+#define NSP32_SG_TABLE_SIZE (sizeof(nsp32_sglun) * MAX_TARGET * MAX_LUN)
 
 /* Auto parameter mode memory map.   */
 /* All values must be little endian. */

WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: GOTO Masanori <gotom@debian.or.jp>
Cc: YOKOTA Hiroshi <yokota@netlab.is.tsukuba.ac.jp>,
	"James E.J. Bottomley" <JBottomley@parallels.com>,
	linux-scsi@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [patch] [SCSI] nsp32: fix an off by one
Date: Thu, 3 Apr 2014 10:28:53 +0300	[thread overview]
Message-ID: <20140403072853.GC14286@mwanda> (raw)

This off by one bug will cause memory corruption when we use every
sglun.

The problem is that NSP32_SG_TABLE_SIZE is too small.  Here is how
it's caculated in the original code:

	sizeof(nsp32_sgtable) * NSP32_SG_SIZE * MAX_TARGET * MAX_LUN

But the problem is that the NSP32_SG_SIZE should be (NSP32_SG_SIZE + 1)
like this:

	sizeof(nsp32_sgtable) * (NSP32_SG_SIZE + 1) * MAX_TARGET * MAX_LUN

Or another more intuitive way to write it would be:

	sizeof(nsp32_sglun) * MAX_TARGET * MAX_LUN

We use NSP32_SG_TABLE_SIZE to allocate data->sg_list which is an array
of nsp32_sglun structs.  The array has MAX_TARGET * MAX_LUN elements.

MAX_TARGET (8) * MAX_LUN (8) = 64 elements.  The missing "+ 1" means
that we only allocate enough space for 63 elements.  In terms of bytes,
the old code allocated 65536 bytes and now it allocates 66048 bytes.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
Static checker stuff.

diff --git a/drivers/scsi/nsp32.h b/drivers/scsi/nsp32.h
index c022182..d94f4cd 100644
--- a/drivers/scsi/nsp32.h
+++ b/drivers/scsi/nsp32.h
@@ -454,7 +454,7 @@ typedef struct _nsp32_sgtable {
 typedef struct _nsp32_sglun {
 	nsp32_sgtable sgt[NSP32_SG_SIZE+1];	/* SG table */
 } __attribute__ ((packed)) nsp32_sglun;
-#define NSP32_SG_TABLE_SIZE (sizeof(nsp32_sgtable) * NSP32_SG_SIZE * MAX_TARGET * MAX_LUN)
+#define NSP32_SG_TABLE_SIZE (sizeof(nsp32_sglun) * MAX_TARGET * MAX_LUN)
 
 /* Auto parameter mode memory map.   */
 /* All values must be little endian. */

             reply	other threads:[~2014-04-03  7:28 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-03  7:28 Dan Carpenter [this message]
2014-04-03  7:28 ` [patch] [SCSI] nsp32: fix an off by one Dan Carpenter

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20140403072853.GC14286@mwanda \
    --to=dan.carpenter@oracle.com \
    --cc=JBottomley@parallels.com \
    --cc=gotom@debian.or.jp \
    --cc=kernel-janitors@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=yokota@netlab.is.tsukuba.ac.jp \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.