[PATCH 2/2] fs: require FMODE_WRITE for F_SET_RW_HINT

[Christoph Hellwig <hch@xxxxxx>]

F_SET_RW_HINT controls the placement of written file data.  A read-only
fd should not allow for that.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/fcntl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 7fc6190da342..12f60c42743a 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -377,6 +377,8 @@ static long fcntl_set_rw_hint(struct file *file, unsigned int cmd,
 
 	if (!inode_owner_or_capable(file_mnt_idmap(file), inode))
 		return -EPERM;
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EBADF;
 
 	if (copy_from_user(&hint, argp, sizeof(hint)))
 		return -EFAULT;
-- 
2.45.2