redonkable
/
remarkable-linux
1
0
Fork 0
Code Releases Activity

seq_file: fix incomplete reset on read from zero offset 

commit cf5eebae2c upstream.

When resetting iterator on a zero offset we need to discard any data
already in the buffer (count), and private state of the iterator (version).

For example this bug results in first line being repeated in /proc/mounts
if doing a zero size read before a non-zero size read.

Reported-by: Rich Felker <dalias@libc.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: e522751d60 ("seq_file: reset iterator to first record for zero offset")
Cc: <stable@vger.kernel.org> # v4.10
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Miklos Szeredi 2017-11-15 11:34:58 +01:00 committed by Greg Kroah-Hartman
parent 0f0fd00739
commit 29b4af7040
1 changed files with 4 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
fs/seq_file.c
View File

@ -181,8 +181,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
* if request is to read from zero offset, reset iterator to first
* record as it might have been already advanced by previous requests
*/
if (*ppos == 0)
if (*ppos == 0) {
m->index = 0;
m->version = 0;
m->count = 0;
}
/* Don't assume *ppos is where we left it */
if (unlikely(*ppos != m->read_pos)) {