CVE-2014-4027 (published 2014-06-23T11:21Z)

The rd_build_device_space function in drivers/target/target_core_rd.c in the Linux kernel before 3.14 does not properly initialize a certain data structure, which allows local users to obtain sensitive information from ramdisk_mcp memory by leveraging access to a SCSI initiator.

Severity: LOW
CVSS v2 base score: 2.3 (AV:A/AC:M/Au:S/C:P/I:N/A:N)

Weakness information:
cwe_id: CWE-200
cwe_name: Exposure of Sensitive Information to an Unauthorized Actor
description: The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
extended_description: 
	   There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker.  Some kinds of sensitive information include:
       
         private, personal information, such as personal messages, financial data, health records, geographic location, or contact details
         system status and environment, such as the operating system and installed packages
		 business secrets and intellectual property
		 network status and configuration
		 the product's own code or internal state
         metadata, e.g. logging of connections or message headers
		 indirect information, such as a discrepancy between two internal operations that can be observed by an outsider
       
	    Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected.  These parties include:
               
                  the product's own users
                  people or organizations whose information is created or used by the product, even if they are not direct product users
		  the product's administrators, including the admins of the system(s) and/or networks on which the product operates
                  the developer
               
	    Information exposures can occur in different ways:
               
                  the code explicitly inserts sensitive information into resources or messages that are intentionally made accessible to unauthorized actors, but should not contain the information - i.e., the information should have been "scrubbed" or "sanitized"
                  a different weakness or mistake indirectly inserts the sensitive information into resources, such as a web script error revealing the full system path of the program.
                  the code manages resources that intentionally contain sensitive information, but the resources are unintentionally made accessible to unauthorized actors. In this case, the information exposure is resultant - i.e., a different weakness enabled the access to the information in the first place.
               
	    It is common practice to describe any loss of confidentiality as an "information exposure," but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read.  CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.
         
         

Fix information:
repo_url: https://github.com/torvalds/linux
commit_details: repo_url: https://github.com/torvalds/linux
author: Nicholas Bellinger
author_date: 2014-01-07 22:40:27+00:00
msg: target/rd: Refactor rd_build_device_space + rd_release_device_space

This patch refactors rd_build_device_space() + rd_release_device_space()
into rd_allocate_sgl_table() + rd_release_device_space() so that they
may be used seperatly for setup + release of protection information
scatterlists.

Also add explicit memset of pages within rd_allocate_sgl_table() based
upon passed 'init_payload' value.

v2 changes:
  - Drop unused sg_table from rd_release_device_space (Wei)

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
repository: repo_url: https://github.com/torvalds/linux
repo_name: torvalds/linux
description: Linux kernel source tree
repo_language: C
owner: torvalds
file_changes: filename: target_core_rd.c
change_type: ModificationType.MODIFY
diff: @@ -78,23 +78,14 @@ static void rd_detach_hba(struct se_hba *hba)
 	hba->hba_ptr = NULL;
 }
 
-/*	rd_release_device_space():
- *
- *
- */
-static void rd_release_device_space(struct rd_dev *rd_dev)
+static u32 rd_release_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *sg_table,
+				 u32 sg_table_count)
 {
-	u32 i, j, page_count = 0, sg_per_table;
-	struct rd_dev_sg_table *sg_table;
 	struct page *pg;
 	struct scatterlist *sg;
+	u32 i, j, page_count = 0, sg_per_table;
 
-	if (!rd_dev->sg_table_array || !rd_dev->sg_table_count)
-		return;
-
-	sg_table = rd_dev->sg_table_array;
-
-	for (i = 0; i < rd_dev->sg_table_count; i++) {
+	for (i = 0; i < sg_table_count; i++) {
 		sg = sg_table[i].sg_table;
 		sg_per_table = sg_table[i].rd_sg_count;
 
@@ -105,16 +96,28 @@ static void rd_release_device_space(struct rd_dev *rd_dev)
 				page_count++;
 			}
 		}
-
 		kfree(sg);
 	}
 
+	kfree(sg_table);
+	return page_count;
+}
+
+static void rd_release_device_space(struct rd_dev *rd_dev)
+{
+	u32 page_count;
+
+	if (!rd_dev->sg_table_array || !rd_dev->sg_table_count)
+		return;
+
+	page_count = rd_release_sgl_table(rd_dev, rd_dev->sg_table_array,
+					  rd_dev->sg_table_count);
+
 	pr_debug("CORE_RD[%u] - Released device space for Ramdisk"
 		" Device ID: %u, pages %u in %u tables total bytes %lu\n",
 		rd_dev->rd_host->rd_host_id, rd_dev->rd_dev_id, page_count,
 		rd_dev->sg_table_count, (unsigned long)page_count * PAGE_SIZE);
 
-	kfree(sg_table);
 	rd_dev->sg_table_array = NULL;
 	rd_dev->sg_table_count = 0;
 }
@@ -124,38 +127,15 @@ static void rd_release_device_space(struct rd_dev *rd_dev)
  *
  *
  */
-static int rd_build_device_space(struct rd_dev *rd_dev)
+static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *sg_table,
+				 u32 total_sg_needed, unsigned char init_payload)
 {
-	u32 i = 0, j, page_offset = 0, sg_per_table, sg_tables, total_sg_needed;
+	u32 i = 0, j, page_offset = 0, sg_per_table;
 	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
 				sizeof(struct scatterlist));
-	struct rd_dev_sg_table *sg_table;
 	struct page *pg;
 	struct scatterlist *sg;
-
-	if (rd_dev->rd_page_count <= 0) {
-		pr_err("Illegal page count: %u for Ramdisk device\n",
-			rd_dev->rd_page_count);
-		return -EINVAL;
-	}
-
-	/* Don't need backing pages for NULLIO */
-	if (rd_dev->rd_flags & RDF_NULLIO)
-		return 0;
-
-	total_sg_needed = rd_dev->rd_page_count;
-
-	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
-
-	sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
-	if (!sg_table) {
-		pr_err("Unable to allocate memory for Ramdisk"
-			" scatterlist tables\n");
-		return -ENOMEM;
-	}
-
-	rd_dev->sg_table_array = sg_table;
-	rd_dev->sg_table_count = sg_tables;
+	unsigned char *p;
 
 	while (total_sg_needed) {
 		sg_per_table = (total_sg_needed > max_sg_per_table) ?
@@ -186,16 +166,59 @@ static int rd_build_device_space(struct rd_dev *rd_dev)
 			}
 			sg_assign_page(&sg[j], pg);
 			sg[j].length = PAGE_SIZE;
+
+			p = kmap(pg);
+			memset(p, init_payload, PAGE_SIZE);
+			kunmap(pg);
 		}
 
 		page_offset += sg_per_table;
 		total_sg_needed -= sg_per_table;
 	}
 
+	return 0;
+}
+
+static int rd_build_device_space(struct rd_dev *rd_dev)
+{
+	struct rd_dev_sg_table *sg_table;
+	u32 sg_tables, total_sg_needed;
+	u32 max_sg_per_table = (RD_MAX_ALLOCATION_SIZE /
+				sizeof(struct scatterlist));
+	int rc;
+
+	if (rd_dev->rd_page_count <= 0) {
+		pr_err("Illegal page count: %u for Ramdisk device\n",
+		       rd_dev->rd_page_count);
+		return -EINVAL;
+	}
+
+	/* Don't need backing pages for NULLIO */
+	if (rd_dev->rd_flags & RDF_NULLIO)
+		return 0;
+
+	total_sg_needed = rd_dev->rd_page_count;
+
+	sg_tables = (total_sg_needed / max_sg_per_table) + 1;
+
+	sg_table = kzalloc(sg_tables * sizeof(struct rd_dev_sg_table), GFP_KERNEL);
+	if (!sg_table) {
+		pr_err("Unable to allocate memory for Ramdisk"
+		       " scatterlist tables\n");
+		return -ENOMEM;
+	}
+
+	rd_dev->sg_table_array = sg_table;
+	rd_dev->sg_table_count = sg_tables;
+
+	rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0x00);
+	if (rc)
+		return rc;
+
 	pr_debug("CORE_RD[%u] - Built Ramdisk Device ID: %u space of"
-		" %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
-		rd_dev->rd_dev_id, rd_dev->rd_page_count,
-		rd_dev->sg_table_count);
+		 " %u pages in %u tables\n", rd_dev->rd_host->rd_host_id,
+		 rd_dev->rd_dev_id, rd_dev->rd_page_count,
+		 rd_dev->sg_table_count);
 
 	return 0;
 }

programming_language: C