[PATCH] sock filter: fix copy of filter from userspace

The sk_unattached_filter_create function is passed a socket
filter structure and the copies the contents of the filter from
userspace. Sparse detected that this code was incorrectly using
memcpy when it needed to use copy_from_user instead.

The only use of sk_unattached_filter_create at present is in
the team driver.

Signed-off-by: Stephen Hemminger <redacted>

--- a/net/core/filter.c	2012-10-09 10:35:03.183141638 -0700
+++ b/net/core/filter.c	2012-10-13 11:33:05.955531440 -0700

@@ -666,7 +666,9 @@ int sk_unattached_filter_create(struct s
 	fp = kmalloc(fsize + sizeof(*fp), GFP_KERNEL);
 	if (!fp)
 		return -ENOMEM;
-	memcpy(fp->insns, fprog->filter, fsize);
+
+	if (copy_from_user(fp->insns, fprog->filter, fsize))
+		return -EFAULT;
 
 	atomic_set(&fp->refcnt, 1);
 	fp->len = fprog->len;

Sat, Oct 13, 2012 at 08:40:32PM CEST, shemminger@vyatta.com wrote:

The sk_unattached_filter_create function is passed a socket
filter structure and the copies the contents of the filter from
userspace. Sparse detected that this code was incorrectly using
memcpy when it needed to use copy_from_user instead.

Hmm. fprog->filter is in this case allocated and filled in kernel.
So memcpy is good.

Not sure how to handle this correctly. Either we remove "__user" or we
redefine "struct sock_fprog" for sk_unattached_filter_create() use.

Any thoughts?

On Sat, 13 Oct 2012 21:19:49 +0200
Jiri Pirko [off-list ref] wrote:

Sat, Oct 13, 2012 at 08:40:32PM CEST, shemminger@vyatta.com wrote:

quoted

The sk_unattached_filter_create function is passed a socket
filter structure and the copies the contents of the filter from
userspace. Sparse detected that this code was incorrectly using
memcpy when it needed to use copy_from_user instead.

Hmm. fprog->filter is in this case allocated and filled in kernel.
So memcpy is good.

Not sure how to handle this correctly. Either we remove "__user" or we
redefine "struct sock_fprog" for sk_unattached_filter_create() use.

Any thoughts?

Or define a different structure for kernel usage versus userspace API.