diff mbox series

scsi: target: tcmu: allocate zeroed pages for data area

Message ID 20211013171606.25197-1-bostroesser@gmail.com (mailing list archive)
State Accepted
Headers show
Series scsi: target: tcmu: allocate zeroed pages for data area | expand

Commit Message

Bodo Stroesser Oct. 13, 2021, 5:16 p.m. UTC
Tcmu populates the data area (used for communication with
userspace) with pages that are allocated by calling
alloc_page(GFP_NOIO).
Therefore previous content of the allocated pages is exposed
to user space. Avoid this by adding __GFP_ZERO flag.

Zeroing the pages does (nearly) not affect tcmu throughput,
because allocated pages are re-used for the data transfers of
later SCSI cmds.

Signed-off-by: Bodo Stroesser <bostroesser@gmail.com>
---
 drivers/target/target_core_user.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Martin K. Petersen Oct. 17, 2021, 2:47 a.m. UTC | #1
Bodo,

> Tcmu populates the data area (used for communication with userspace)
> with pages that are allocated by calling alloc_page(GFP_NOIO).
> Therefore previous content of the allocated pages is exposed to user
> space. Avoid this by adding __GFP_ZERO flag.

Applied to 5.16/scsi-staging, thanks!
Martin K. Petersen Oct. 21, 2021, 3:42 a.m. UTC | #2
On Wed, 13 Oct 2021 19:16:06 +0200, Bodo Stroesser wrote:

> Tcmu populates the data area (used for communication with
> userspace) with pages that are allocated by calling
> alloc_page(GFP_NOIO).
> Therefore previous content of the allocated pages is exposed
> to user space. Avoid this by adding __GFP_ZERO flag.
> 
> Zeroing the pages does (nearly) not affect tcmu throughput,
> because allocated pages are re-used for the data transfers of
> later SCSI cmds.
> 
> [...]

Applied to 5.16/scsi-queue, thanks!

[1/1] scsi: target: tcmu: allocate zeroed pages for data area
      https://git.kernel.org/mkp/scsi/c/1d2ac7b69d6a
diff mbox series

Patch

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index dc220fad06fa..a19e53877b0b 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -5,6 +5,7 @@ 
  * Copyright (C) 2015 Arrikto, Inc.
  * Copyright (C) 2017 Chinamobile, Inc.
  */
+#include <linux/delay.h>
 
 #include <linux/spinlock.h>
 #include <linux/module.h>
@@ -523,8 +524,8 @@  static inline int tcmu_get_empty_block(struct tcmu_dev *udev,
 	rcu_read_unlock();
 
 	for (i = cnt; i < page_cnt; i++) {
-		/* try to get new page from the mm */
-		page = alloc_page(GFP_NOIO);
+		/* try to get new zeroed page from the mm */
+		page = alloc_page(GFP_NOIO | __GFP_ZERO);
 		if (!page)
 			break;