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* [PATCH] scsi: avoid a double-fetch and a redundant copy
@ 2018-12-25 20:15 Kangjie Lu
  2018-12-25 21:11 ` kbuild test robot
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Kangjie Lu @ 2018-12-25 20:15 UTC (permalink / raw)
  To: kjlu
  Cc: pakki001, Doug Gilbert, James E.J. Bottomley, Martin K. Petersen,
	linux-scsi, linux-kernel

What we need is only "pack_id", so do not create a heap object or copy
the whole object in. The fix efficiently copies "pack_id" only.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/scsi/sg.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index c6ad00703c5b..4dacbfffd113 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -446,16 +446,8 @@ sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
 		}
 		if (old_hdr->reply_len < 0) {
 			if (count >= SZ_SG_IO_HDR) {
-				sg_io_hdr_t *new_hdr;
-				new_hdr = kmalloc(SZ_SG_IO_HDR, GFP_KERNEL);
-				if (!new_hdr) {
-					retval = -ENOMEM;
-					goto free_old_hdr;
-				}
-				retval =__copy_from_user
-				    (new_hdr, buf, SZ_SG_IO_HDR);
-				req_pack_id = new_hdr->pack_id;
-				kfree(new_hdr);
+				retval = get_user(req_pack_id,
+						&((sg_io_hdr_t *)buf->pack_id));
 				if (retval) {
 					retval = -EFAULT;
 					goto free_old_hdr;
-- 
2.17.2 (Apple Git-113)


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] scsi: avoid a double-fetch and a redundant copy
@ 2018-12-25 22:47 Kangjie Lu
  0 siblings, 0 replies; 6+ messages in thread
From: Kangjie Lu @ 2018-12-25 22:47 UTC (permalink / raw)
  To: kjlu
  Cc: pakki001, Doug Gilbert, James E.J. Bottomley, Martin K. Petersen,
	Ingo Molnar, Peter Zijlstra, linux-scsi, linux-kernel

What we need is only "pack_id", so do not create a heap object or copy
the whole object in. The fix efficiently copies "pack_id" only.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/scsi/sg.c   |  4 ++--
 kernel/sched/core.c | 18 ++++++++++++------
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 41774e4f9508..75842ceabc7f 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -446,8 +446,8 @@ sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
 		}
 		if (old_hdr->reply_len < 0) {
 			if (count >= SZ_SG_IO_HDR) {
-				retval = get_user(req_pack_id,
-						&((sg_io_hdr_t *)buf->pack_id));
+				retval =
+					get_user(req_pack_id, &(sg_io_hdr_t __user *)buf->pack_id);
 				if (retval) {
 					retval = -EFAULT;
 					goto free_old_hdr;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6fedf3a98581..0a55bdce9a42 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4447,7 +4447,7 @@ do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
  */
 static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
 {
-	u32 size;
+	u32 size, size_cp;
 	int ret;
 
 	if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
@@ -4460,15 +4460,17 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a
 	if (ret)
 		return ret;
 
+	size_cp = size;
+
 	/* Bail out on silly large: */
 	if (size > PAGE_SIZE)
 		goto err_size;
 
 	/* ABI compatibility quirk: */
 	if (!size)
-		size = SCHED_ATTR_SIZE_VER0;
+		size_cp = SCHED_ATTR_SIZE_VER0;
 
-	if (size < SCHED_ATTR_SIZE_VER0)
+	else if (size < SCHED_ATTR_SIZE_VER0)
 		goto err_size;
 
 	/*
@@ -4483,7 +4485,7 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a
 		unsigned char val;
 
 		addr = (void __user *)uattr + sizeof(*attr);
-		end  = (void __user *)uattr + size;
+		end  = (void __user *)uattr + size_cp;
 
 		for (; addr < end; addr++) {
 			ret = get_user(val, addr);
@@ -4492,13 +4494,17 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a
 			if (val)
 				goto err_size;
 		}
-		size = sizeof(*attr);
+		size_cp = sizeof(*attr);
 	}
 
-	ret = copy_from_user(attr, uattr, size);
+	ret = copy_from_user(attr, uattr, size_cp);
 	if (ret)
 		return -EFAULT;
 
+	/* Sanity check if size was changed in user space */
+	if (attr->size != size)
+		return -EINVAL;
+
 	/*
 	 * XXX: Do we want to be lenient like existing syscalls; or do we want
 	 * to be strict and return an error on out-of-bounds values?
-- 
2.17.2 (Apple Git-113)


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-01-09  7:26 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-12-25 20:15 [PATCH] scsi: avoid a double-fetch and a redundant copy Kangjie Lu
2018-12-25 21:11 ` kbuild test robot
2018-12-25 21:12 ` kbuild test robot
2018-12-26  6:49 ` Douglas Gilbert
2019-01-09  7:25   ` [PATCH v2] " Kangjie Lu
2018-12-25 22:47 [PATCH] " Kangjie Lu

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