[PATCH] [media] dvb_frontend: Use memdup_user() rather than duplicating its implementation

From: SF Markus Elfring
Date: Fri Aug 19 2016 - 04:17:50 EST


From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 19 Aug 2016 10:04:54 +0200

* Reuse existing functionality from memdup_user() instead of keeping
duplicate source code.

This issue was detected by using the Coccinelle software.

* Return directly if this copy operation failed.

* Replace the specification of data structures by pointer dereferences
to make the corresponding size determination a bit safer according to
the Linux coding style convention.

Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/media/dvb-core/dvb_frontend.c | 28 ++++++----------------------
1 file changed, 6 insertions(+), 22 deletions(-)

diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index be99c8d..01511e5 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -1969,17 +1969,9 @@ static int dvb_frontend_ioctl_properties(struct file *file,
if ((tvps->num == 0) || (tvps->num > DTV_IOCTL_MAX_MSGS))
return -EINVAL;

- tvp = kmalloc(tvps->num * sizeof(struct dtv_property), GFP_KERNEL);
- if (!tvp) {
- err = -ENOMEM;
- goto out;
- }
-
- if (copy_from_user(tvp, (void __user *)tvps->props,
- tvps->num * sizeof(struct dtv_property))) {
- err = -EFAULT;
- goto out;
- }
+ tvp = memdup_user(tvps->props, tvps->num * sizeof(*tvp));
+ if (IS_ERR(tvp))
+ return PTR_ERR(tvp);

for (i = 0; i < tvps->num; i++) {
err = dtv_property_process_set(fe, tvp + i, file);
@@ -2002,17 +1994,9 @@ static int dvb_frontend_ioctl_properties(struct file *file,
if ((tvps->num == 0) || (tvps->num > DTV_IOCTL_MAX_MSGS))
return -EINVAL;

- tvp = kmalloc(tvps->num * sizeof(struct dtv_property), GFP_KERNEL);
- if (!tvp) {
- err = -ENOMEM;
- goto out;
- }
-
- if (copy_from_user(tvp, (void __user *)tvps->props,
- tvps->num * sizeof(struct dtv_property))) {
- err = -EFAULT;
- goto out;
- }
+ tvp = memdup_user(tvps->props, tvps->num * sizeof(*tvp));
+ if (IS_ERR(tvp))
+ return PTR_ERR(tvp);

/*
* Let's use our own copy of property cache, in order to
--
2.9.3