From: Arnd Bergmann Date: Fri, 7 Feb 2020 16:55:48 +0000 (+0100) Subject: compat_ioctl: fix FIONREAD on devices X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=0a061743af93f472687b8c69b0d539d1f12f3fd2;p=openwrt%2Fstaging%2Fblogic.git 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: 77b9040195de ("compat_ioctl: simplify the implementation") Reported-and-tested-by: Christian Zigotzky Reported-and-tested-by: youling257 Signed-off-by: Arnd Bergmann --- diff --git a/fs/ioctl.c b/fs/ioctl.c index 7c9a5df5a597..5152c98cfc30 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -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);