fs: check FMODE_WRITE in __kernel_write

Add a WARN_ON_ONCE if the file isn't actually open for write.  This
matches the check done in vfs_write, but actually warn warns as a
kernel user calling write on a file not opened for writing is a pretty
obvious programming error.

Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Christoph Hellwig 2020-05-08 08:55:03 +02:00
parent 9db9775224
commit a01ac27be4

View file

@ -505,6 +505,8 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t
const char __user *p;
ssize_t ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_WRITE)))
return -EBADF;
if (!(file->f_mode & FMODE_CAN_WRITE))
return -EINVAL;