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vfs: Don't let __fdget_pos() get FMODE_PATH files 

Commit bd2a31d522 ("get rid of fget_light()") introduced the
__fdget_pos() function, which returns the resulting file pointer and
fdput flags combined in an 'unsigned long'.  However, it also changed the
behavior to return files with FMODE_PATH set, which shouldn't happen
because read(), write(), lseek(), etc. aren't allowed on such files.
This commit restores the old behavior.

This regression actually had no effect on read() and write() since
FMODE_READ and FMODE_WRITE are not set on file descriptors opened with
O_PATH, but it did cause lseek() on a file descriptor opened with O_PATH
to fail with ESPIPE rather than EBADF.

Signed-off-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Eric Biggers 2014-03-16 15:47:48 -05:00 committed by Al Viro
parent d7a15f8d07
commit 99aea68134
1 changed files with 4 additions and 15 deletions
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19
fs/file.c
View File

@ -713,27 +713,16 @@ unsigned long __fdget_raw(unsigned int fd)
unsigned long __fdget_pos(unsigned int fd)
{
struct files_struct *files = current->files;
struct file *file;
unsigned long v;
unsigned long v = __fdget(fd);
struct file *file = (struct file *)(v & ~3);
if (atomic_read(&files->count) == 1) {
file = __fcheck_files(files, fd);
v = 0;
} else {
file = __fget(fd, 0);
v = FDPUT_FPUT;
}
if (!file)
return 0;
if (file->f_mode & FMODE_ATOMIC_POS) {
if (file && (file->f_mode & FMODE_ATOMIC_POS)) {
if (file_count(file) > 1) {
v |= FDPUT_POS_UNLOCK;
mutex_lock(&file->f_pos_lock);
}
}
return v | (unsigned long)file;
return v;
}
/*