From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Subject: [patch] [SCSI] nsp32: fix an off by one Date: Thu, 3 Apr 2014 10:28:53 +0300 Message-ID: <20140403072853.GC14286@mwanda> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: kernel-janitors-owner@vger.kernel.org To: GOTO Masanori Cc: YOKOTA Hiroshi , "James E.J. Bottomley" , linux-scsi@vger.kernel.org, kernel-janitors@vger.kernel.org List-Id: linux-scsi@vger.kernel.org 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 --- 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. */