[3.16.y-ckt stable] Patch "target/file: Fix BUG() when CONFIG_DEBUG_SG=y and DIF protection enabled" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    target/file: Fix BUG() when CONFIG_DEBUG_SG=y and DIF protection enabled

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From e5cbd8f7b8897a34b940ed7e4334bb5cc1f6dbe6 Mon Sep 17 00:00:00 2001
From: Akinobu Mita <akinobu.mita at gmail.com>
Date: Mon, 13 Apr 2015 23:21:56 +0900
Subject: target/file: Fix BUG() when CONFIG_DEBUG_SG=y and DIF protection
 enabled

commit 38da0f49e8aa1649af397d53f88e163d0e60c058 upstream.

When CONFIG_DEBUG_SG=y and DIF protection support enabled, kernel
BUG()s are triggered due to the following two issues:

1) prot_sg is not initialized by sg_init_table().

When CONFIG_DEBUG_SG=y, scatterlist helpers check sg entry has a
correct magic value.

2) vmalloc'ed buffer is passed to sg_set_buf().

sg_set_buf() uses virt_to_page() to convert virtual address to struct
page, but it doesn't work with vmalloc address.  vmalloc_to_page()
should be used instead.  As prot_buf isn't usually too large, so
fix it by allocating prot_buf by kmalloc instead of vmalloc.

Signed-off-by: Akinobu Mita <akinobu.mita at gmail.com>
Cc: Sagi Grimberg <sagig at mellanox.com>
Cc: "Martin K. Petersen" <martin.petersen at oracle.com>
Cc: Christoph Hellwig <hch at lst.de>
Cc: "James E.J. Bottomley" <James.Bottomley at HansenPartnership.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/target/target_core_file.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 6f9f0c499813..e031ea8895e5 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -273,7 +273,7 @@ static int fd_do_prot_rw(struct se_cmd *cmd, struct fd_prot *fd_prot,
 		     se_dev->prot_length;

 	if (!is_write) {
-		fd_prot->prot_buf = vzalloc(prot_size);
+		fd_prot->prot_buf = kzalloc(prot_size, GFP_KERNEL);
 		if (!fd_prot->prot_buf) {
 			pr_err("Unable to allocate fd_prot->prot_buf\n");
 			return -ENOMEM;
@@ -285,9 +285,10 @@ static int fd_do_prot_rw(struct se_cmd *cmd, struct fd_prot *fd_prot,
 					   fd_prot->prot_sg_nents, GFP_KERNEL);
 		if (!fd_prot->prot_sg) {
 			pr_err("Unable to allocate fd_prot->prot_sg\n");
-			vfree(fd_prot->prot_buf);
+			kfree(fd_prot->prot_buf);
 			return -ENOMEM;
 		}
+		sg_init_table(fd_prot->prot_sg, fd_prot->prot_sg_nents);
 		size = prot_size;

 		for_each_sg(fd_prot->prot_sg, sg, fd_prot->prot_sg_nents, i) {
@@ -317,7 +318,7 @@ static int fd_do_prot_rw(struct se_cmd *cmd, struct fd_prot *fd_prot,

 	if (is_write || ret < 0) {
 		kfree(fd_prot->prot_sg);
-		vfree(fd_prot->prot_buf);
+		kfree(fd_prot->prot_buf);
 	}

 	return ret;
@@ -652,11 +653,11 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 						 0, fd_prot.prot_sg, 0);
 			if (rc) {
 				kfree(fd_prot.prot_sg);
-				vfree(fd_prot.prot_buf);
+				kfree(fd_prot.prot_buf);
 				return rc;
 			}
 			kfree(fd_prot.prot_sg);
-			vfree(fd_prot.prot_buf);
+			kfree(fd_prot.prot_buf);
 		}
 	} else {
 		memset(&fd_prot, 0, sizeof(struct fd_prot));
@@ -672,7 +673,7 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 						  0, fd_prot.prot_sg, 0);
 			if (rc) {
 				kfree(fd_prot.prot_sg);
-				vfree(fd_prot.prot_buf);
+				kfree(fd_prot.prot_buf);
 				return rc;
 			}
 		}
@@ -703,7 +704,7 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,

 	if (ret < 0) {
 		kfree(fd_prot.prot_sg);
-		vfree(fd_prot.prot_buf);
+		kfree(fd_prot.prot_buf);
 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 	}