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From: Julia Lawall on 22 May 2010 04:30
From: Julia Lawall <julia(a)diku.dk>

Use memdup_user when user data is immediately copied into the allocated
region. Note that in the second case, the ++i is no longer necessary, as
the last value is already freed if needed by the call to memdup_user.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression from,to,size,flag;
position p;
identifier l1,l2;
@@

- to = \(kmalloc@p\|kzalloc@p\)(size,flag);
+ to = memdup_user(from,size);
if (
- to==NULL
+ IS_ERR(to)
|| ...) {
<+... when != goto l1;
- -ENOMEM
+ PTR_ERR(to)
...+>
}
- if (copy_from_user(to, from, size) != 0) {
- <+... when != goto l2;
- -EFAULT
- ...+>
- }
// </smpl>

Signed-off-by: Julia Lawall <julia(a)diku.dk>

---
drivers/i2c/i2c-dev.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index e0694e4..03e9ef8 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -167,13 +167,9 @@ static ssize_t i2cdev_write(struct file *file, const char __user *buf,
if (count > 8192)
count = 8192;

- tmp = kmalloc(count, GFP_KERNEL);
- if (tmp == NULL)
- return -ENOMEM;
- if (copy_from_user(tmp, buf, count)) {
- kfree(tmp);
- return -EFAULT;
- }
+ tmp = memdup_user(buf, count);
+ if (IS_ERR(tmp))
+ return PTR_ERR(tmp);

pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
iminor(file->f_path.dentry->d_inode), count);
@@ -247,15 +243,9 @@ static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
break;
}
data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
- rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
- if (rdwr_pa[i].buf == NULL) {
- res = -ENOMEM;
- break;
- }
- if (copy_from_user(rdwr_pa[i].buf, data_ptrs[i],
- rdwr_pa[i].len)) {
- ++i; /* Needs to be kfreed too */
- res = -EFAULT;
+ rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
+ if (IS_ERR(rdwr_pa[i].buf)) {
+ res = PTR_ERR(rdwr_pa[i].buf);
break;
}
}
--
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Prev: [PATCH 20/27] drivers/s390/net: Use memdup_user
Next: [PATCH 23/27] drivers/net/wireless/prism54: Use memdup_user