Re: /proc/bus/pci IOCTL breakage

David Miller
2007-07-27T06:04:44Z

From: David Miller <davem@davemloft.net>
Date: Thu, 26 Jul 2007 19:07:51 -0700 (PDT)

> Two ways to fix:
>
> 1) Make the PROC wrapper call ->unlocked_ioctl() or ->ioctl()
> as a fallback of ->compat_ioctl is NULL.
>
> 2) Make proc_bus_pci_operations provide a .compat_ioctl method,
> but then we'll need to audit the entire tree for cases like
> this and make the same fix.
>
> Because it's easier to validate that all cases are covered,
> I think #1 is the preferred fix.

Here is my suggested fix.

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 right thing.

To be honest, the other unlocked_ioctl fallback scheme in
this file should be scrutinized for similar problems.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 94e2c1a..a5b0dfd 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;
}