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compat_ioctl: fix FIONREAD on devices 

My final cleanup patch for sys_compat_ioctl() introduced a regression on
the FIONREAD ioctl command, which is used for both regular and special
files, but only works on regular files after my patch, as I had missed
the warning that Al Viro put into a comment right above it.

Change it back so it can work on any file again by moving the implementation
to do_vfs_ioctl() instead.

Fixes: 77b9040195 ("compat_ioctl: simplify the implementation")
Reported-and-tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Reported-and-tested-by: youling257 <youling257@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Arnd Bergmann 2020-02-07 17:55:48 +01:00
parent 77b9040195
commit 0a061743af
1 changed files with 7 additions and 4 deletions
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11
fs/ioctl.c
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@ -523,13 +523,9 @@ static int compat_ioctl_preallocate(struct file *file, int mode,
static int file_ioctl(struct file *filp, unsigned int cmd, int __user *p)
{
struct inode *inode = file_inode(filp);
switch (cmd) {
case FIBMAP:
return ioctl_fibmap(filp, p);
case FIONREAD:
return put_user(i_size_read(inode) - filp->f_pos, p);
case FS_IOC_RESVSP:
case FS_IOC_RESVSP64:
return ioctl_preallocate(filp, 0, p);
@ -721,6 +717,13 @@ static int do_vfs_ioctl(struct file *filp, unsigned int fd,
case FIDEDUPERANGE:
return ioctl_file_dedupe_range(filp, argp);
case FIONREAD:
if (!S_ISREG(inode->i_mode))
return vfs_ioctl(filp, cmd, arg);
return put_user(i_size_read(inode) - filp->f_pos,
(int __user *)argp);
default:
if (S_ISREG(inode->i_mode))
return file_ioctl(filp, cmd, argp);