Merge branch 'gadget' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull gadgetfs fixes from Al Viro:
 "Assorted fixes around AIO on gadgetfs: leaks, use-after-free, troubles
  caused by ->f_op flipping"

* 'gadget' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  gadgetfs: really get rid of switching ->f_op
  gadgetfs: get rid of flipping ->f_op in ep_config()
  gadget: switch ep_io_operations to ->read_iter/->write_iter
  gadgetfs: use-after-free in ->aio_read()
  gadget/function/f_fs.c: switch to ->{read,write}_iter()
  gadget/function/f_fs.c: use put iov_iter into io_data
  gadget/function/f_fs.c: close leaks
  move iov_iter.c from mm/ to lib/
  new helper: dup_iter()

drivers/usb/gadget/function/f_fs.c

@@ -144,10 +144,9 @@ struct ffs_io_data {
 	bool read;
 
 	struct kiocb *kiocb;
-	const struct iovec *iovec;
-	unsigned long nr_segs;
-	char __user *buf;
-	size_t len;
+	struct iov_iter data;
+	const void *to_free;
+	char *buf;
 
 	struct mm_struct *mm;
 	struct work_struct work;
@@ -649,29 +648,10 @@ static void ffs_user_copy_worker(struct work_struct *work)
 					 io_data->req->actual;
 
 	if (io_data->read && ret > 0) {
-		int i;
-		size_t pos = 0;
-
-		/*
-		 * Since req->length may be bigger than io_data->len (after
-		 * being rounded up to maxpacketsize), we may end up with more
-		 * data then user space has space for.
-		 */
-		ret = min_t(int, ret, io_data->len);
-
 		use_mm(io_data->mm);
-		for (i = 0; i < io_data->nr_segs; i++) {
-			size_t len = min_t(size_t, ret - pos,
-					io_data->iovec[i].iov_len);
-			if (!len)
-				break;
-			if (unlikely(copy_to_user(io_data->iovec[i].iov_base,
-						 &io_data->buf[pos], len))) {
+		ret = copy_to_iter(io_data->buf, ret, &io_data->data);
+		if (iov_iter_count(&io_data->data))
 			ret = -EFAULT;
-				break;
-			}
-			pos += len;
-		}
 		unuse_mm(io_data->mm);
 	}
 
@@ -684,7 +664,7 @@ static void ffs_user_copy_worker(struct work_struct *work)
 
 	io_data->kiocb->private = NULL;
 	if (io_data->read)
-		kfree(io_data->iovec);
+		kfree(io_data->to_free);
 	kfree(io_data->buf);
 	kfree(io_data);
 }
@@ -743,6 +723,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 		 * before the waiting completes, so do not assign to 'gadget' earlier
 		 */
 		struct usb_gadget *gadget = epfile->ffs->gadget;
+		size_t copied;
 
 		spin_lock_irq(&epfile->ffs->eps_lock);
 		/* In the meantime, endpoint got disabled or changed. */
@@ -750,34 +731,21 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 			spin_unlock_irq(&epfile->ffs->eps_lock);
 			return -ESHUTDOWN;
 		}
+		data_len = iov_iter_count(&io_data->data);
 		/*
 		 * Controller may require buffer size to be aligned to
 		 * maxpacketsize of an out endpoint.
 		 */
-		data_len = io_data->read ?
-			   usb_ep_align_maybe(gadget, ep->ep, io_data->len) :
-			   io_data->len;
+		if (io_data->read)
+			data_len = usb_ep_align_maybe(gadget, ep->ep, data_len);
 		spin_unlock_irq(&epfile->ffs->eps_lock);
 
 		data = kmalloc(data_len, GFP_KERNEL);
 		if (unlikely(!data))
 			return -ENOMEM;
-		if (io_data->aio && !io_data->read) {
-			int i;
-			size_t pos = 0;
-			for (i = 0; i < io_data->nr_segs; i++) {
-				if (unlikely(copy_from_user(&data[pos],
-					     io_data->iovec[i].iov_base,
-					     io_data->iovec[i].iov_len))) {
-					ret = -EFAULT;
-					goto error;
-				}
-				pos += io_data->iovec[i].iov_len;
-			}
-		} else {
-			if (!io_data->read &&
-			    unlikely(__copy_from_user(data, io_data->buf,
-						      io_data->len))) {
+		if (!io_data->read) {
+			copied = copy_from_iter(data, data_len, &io_data->data);
+			if (copied != data_len) {
 				ret = -EFAULT;
 				goto error;
 			}
@@ -876,10 +844,8 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 				 */
 				ret = ep->status;
 				if (io_data->read && ret > 0) {
-					ret = min_t(size_t, ret, io_data->len);
-
-					if (unlikely(copy_to_user(io_data->buf,
-						data, ret)))
+					ret = copy_to_iter(data, ret, &io_data->data);
+					if (unlikely(iov_iter_count(&io_data->data)))
 						ret = -EFAULT;
 				}
 			}
@@ -898,37 +864,6 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 	return ret;
 }
 
-static ssize_t
-ffs_epfile_write(struct file *file, const char __user *buf, size_t len,
-		 loff_t *ptr)
-{
-	struct ffs_io_data io_data;
-
-	ENTER();
-
-	io_data.aio = false;
-	io_data.read = false;
-	io_data.buf = (char * __user)buf;
-	io_data.len = len;
-
-	return ffs_epfile_io(file, &io_data);
-}
-
-static ssize_t
-ffs_epfile_read(struct file *file, char __user *buf, size_t len, loff_t *ptr)
-{
-	struct ffs_io_data io_data;
-
-	ENTER();
-
-	io_data.aio = false;
-	io_data.read = true;
-	io_data.buf = buf;
-	io_data.len = len;
-
-	return ffs_epfile_io(file, &io_data);
-}
-
 static int
 ffs_epfile_open(struct inode *inode, struct file *file)
 {
@@ -965,67 +900,86 @@ static int ffs_aio_cancel(struct kiocb *kiocb)
 	return value;
 }
 
-static ssize_t ffs_epfile_aio_write(struct kiocb *kiocb,
-				    const struct iovec *iovec,
-				    unsigned long nr_segs, loff_t loff)
+static ssize_t ffs_epfile_write_iter(struct kiocb *kiocb, struct iov_iter *from)
 {
-	struct ffs_io_data *io_data;
+	struct ffs_io_data io_data, *p = &io_data;
+	ssize_t res;
 
 	ENTER();
 
-	io_data = kmalloc(sizeof(*io_data), GFP_KERNEL);
-	if (unlikely(!io_data))
+	if (!is_sync_kiocb(kiocb)) {
+		p = kmalloc(sizeof(io_data), GFP_KERNEL);
+		if (unlikely(!p))
 			return -ENOMEM;
+		p->aio = true;
+	} else {
+		p->aio = false;
+	}
 
-	io_data->aio = true;
-	io_data->read = false;
-	io_data->kiocb = kiocb;
-	io_data->iovec = iovec;
-	io_data->nr_segs = nr_segs;
-	io_data->len = kiocb->ki_nbytes;
-	io_data->mm = current->mm;
+	p->read = false;
+	p->kiocb = kiocb;
+	p->data = *from;
+	p->mm = current->mm;
 
-	kiocb->private = io_data;
+	kiocb->private = p;
 
 	kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
 
-	return ffs_epfile_io(kiocb->ki_filp, io_data);
+	res = ffs_epfile_io(kiocb->ki_filp, p);
+	if (res == -EIOCBQUEUED)
+		return res;
+	if (p->aio)
+		kfree(p);
+	else
+		*from = p->data;
+	return res;
 }
 
-static ssize_t ffs_epfile_aio_read(struct kiocb *kiocb,
-				   const struct iovec *iovec,
-				   unsigned long nr_segs, loff_t loff)
+static ssize_t ffs_epfile_read_iter(struct kiocb *kiocb, struct iov_iter *to)
 {
-	struct ffs_io_data *io_data;
-	struct iovec *iovec_copy;
+	struct ffs_io_data io_data, *p = &io_data;
+	ssize_t res;
 
 	ENTER();
 
-	iovec_copy = kmalloc_array(nr_segs, sizeof(*iovec_copy), GFP_KERNEL);
-	if (unlikely(!iovec_copy))
+	if (!is_sync_kiocb(kiocb)) {
+		p = kmalloc(sizeof(io_data), GFP_KERNEL);
+		if (unlikely(!p))
 			return -ENOMEM;
+		p->aio = true;
+	} else {
+		p->aio = false;
+	}
 
-	memcpy(iovec_copy, iovec, sizeof(struct iovec)*nr_segs);
-
-	io_data = kmalloc(sizeof(*io_data), GFP_KERNEL);
-	if (unlikely(!io_data)) {
-		kfree(iovec_copy);
+	p->read = true;
+	p->kiocb = kiocb;
+	if (p->aio) {
+		p->to_free = dup_iter(&p->data, to, GFP_KERNEL);
+		if (!p->to_free) {
+			kfree(p);
 			return -ENOMEM;
 		}
+	} else {
+		p->data = *to;
+		p->to_free = NULL;
+	}
+	p->mm = current->mm;
 
-	io_data->aio = true;
-	io_data->read = true;
-	io_data->kiocb = kiocb;
-	io_data->iovec = iovec_copy;
-	io_data->nr_segs = nr_segs;
-	io_data->len = kiocb->ki_nbytes;
-	io_data->mm = current->mm;
-
-	kiocb->private = io_data;
+	kiocb->private = p;
 
 	kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
 
-	return ffs_epfile_io(kiocb->ki_filp, io_data);
+	res = ffs_epfile_io(kiocb->ki_filp, p);
+	if (res == -EIOCBQUEUED)
+		return res;
+
+	if (p->aio) {
+		kfree(p->to_free);
+		kfree(p);
+	} else {
+		*to = p->data;
+	}
+	return res;
 }
 
 static int
@@ -1105,10 +1059,10 @@ static const struct file_operations ffs_epfile_operations = {
 	.llseek =	no_llseek,
 
 	.open =		ffs_epfile_open,
-	.write =	ffs_epfile_write,
-	.read =		ffs_epfile_read,
-	.aio_write =	ffs_epfile_aio_write,
-	.aio_read =	ffs_epfile_aio_read,
+	.write =	new_sync_write,
+	.read =		new_sync_read,
+	.write_iter =	ffs_epfile_write_iter,
+	.read_iter =	ffs_epfile_read_iter,
 	.release =	ffs_epfile_release,
 	.unlocked_ioctl =	ffs_epfile_ioctl,
 };

include/linux/uio.h

@@ -98,6 +98,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 			size_t maxsize, size_t *start);
 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 
+const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
+
 static inline size_t iov_iter_count(struct iov_iter *i)
 {
 	return i->count;

lib/Makefile

@@ -24,7 +24,7 @@ obj-y	+= lockref.o
 
 obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
 	 bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
-	 gcd.o lcm.o list_sort.o uuid.o flex_array.o clz_ctz.o \
+	 gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \
 	 bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \
 	 percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o
 obj-y += string_helpers.o

mm/iov_iter.c → lib/iov_iter.c

@@ -751,3 +751,18 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
 	return npages;
 }
 EXPORT_SYMBOL(iov_iter_npages);
+
+const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
+{
+	*new = *old;
+	if (new->type & ITER_BVEC)
+		return new->bvec = kmemdup(new->bvec,
+				    new->nr_segs * sizeof(struct bio_vec),
+				    flags);
+	else
+		/* iovec and kvec have identical layout */
+		return new->iov = kmemdup(new->iov,
+				   new->nr_segs * sizeof(struct iovec),
+				   flags);
+}
+EXPORT_SYMBOL(dup_iter);

mm/Makefile

@@ -21,7 +21,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o \
 			   mm_init.o mmu_context.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   iov_iter.o debug.o $(mmu-y)
+			   debug.o $(mmu-y)
 
 obj-y += init-mm.o