Re: Yet another pipe related oops.

[Al Viro <viro@ZenIV.linux.org.uk>]

On Wed, Mar 27, 2013 at 09:51:27AM -0400, Dave Jones wrote:

> Could be that Al's patches refactored this bug away, or it could just be
> that I've been lucky the last few weeks, and just haven't had the right
> entropy to get the sequence of events right..
> 
> thoughts ?

Actually, that's my fault - check lost in patch reordering.  My apologies ;-/
Eventually, we want that in fs/splice.c side of things (no point repeating it
for every buffer, after all), but for now this is the obvious minimal fix.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
diff --git a/fs/read_write.c b/fs/read_write.c
index f7b5a23..e6ddc8d 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -424,6 +424,9 @@ ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t
 	const char __user *p;
 	ssize_t ret;
 
+	if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
+		return -EINVAL;
+
 	old_fs = get_fs();
 	set_fs(get_ds());
 	p = (__force const char __user *)buf;