Fix procfs compat_ioctl regression

It is important to only provide the compat_ioctl method
if the downstream de->proc_fops does too, otherwise this
utterly confuses the logic in fs/compat_ioctl.c and we
end up doing the wrong thing.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 2 deletions

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 94e2c1adf184..a5b0dfd89a17 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -386,6 +386,19 @@ static const struct file_operations proc_reg_file_ops = {
         .release        = proc_reg_release,
 };
 
+#ifdef CONFIG_COMPAT
+static const struct file_operations proc_reg_file_ops_no_compat = {
+        .llseek         = proc_reg_llseek,
+        .read           = proc_reg_read,
+        .write          = proc_reg_write,
+        .poll           = proc_reg_poll,
+        .unlocked_ioctl = proc_reg_unlocked_ioctl,
+        .mmap           = proc_reg_mmap,
+        .open           = proc_reg_open,
+        .release        = proc_reg_release,
+};
+#endif
+
 struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
                                 struct proc_dir_entry *de)
 {
@@ -413,8 +426,15 @@ struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
                 if (de->proc_iops)
                         inode->i_op = de->proc_iops;
                 if (de->proc_fops) {
-                        if (S_ISREG(inode->i_mode))
-                                inode->i_fop = &proc_reg_file_ops;
+                        if (S_ISREG(inode->i_mode)) {
+#ifdef CONFIG_COMPAT
+                                if (!de->proc_fops->compat_ioctl)
+                                        inode->i_fop =
+                                                &proc_reg_file_ops_no_compat;
+                                else
+#endif
+                                        inode->i_fop = &proc_reg_file_ops;
+                        }
                         else
                                 inode->i_fop = de->proc_fops;
                 }