JFFS2 has possible race when setting file attributes
Dmitry Bazhenov
atrey at emcraft.com
Fri May 5 08:44:33 EDT 2006
On Friday 05 May 2006 15:54, David Woodhouse wrote:
> Thanks. Please could you resend, including a 'Signed-off-by:' line?
I posted it to the list, but it didn't appear. So, I repost it.
It seems like there is a potential race in the function jffs2_do_setattr() in
the case when attributes of a symlink are updated. The symlink metadata is
read without having f->sem locked.
The following patch should fix the race.
Signed-off-by: Dmitry Bazhenov <atrey at emcraft.com>
--- a/fs/jffs2/fs.c 2006-04-29 18:51:53.000000000 +0400
+++ b/fs/jffs2/fs.c 2006-05-04 17:32:09.000000000 +0400
@@ -56,15 +56,20 @@ static int jffs2_do_setattr (struct inod
mdatalen = sizeof(dev);
D1(printk(KERN_DEBUG "jffs2_setattr(): Writing %d bytes of
kdev_t\n", mdatalen));
} else if (S_ISLNK(inode->i_mode)) {
+ down(&f->sem);
mdatalen = f->metadata->size;
mdata = kmalloc(f->metadata->size, GFP_USER);
- if (!mdata)
+ if (!mdata) {
+ up(&f->sem);
return -ENOMEM;
+ }
ret = jffs2_read_dnode(c, f, f->metadata, mdata, 0, mdatalen);
if (ret) {
+ up(&f->sem);
kfree(mdata);
return ret;
}
+ up(&f->sem);
D1(printk(KERN_DEBUG "jffs2_setattr(): Writing %d bytes of
symlink target\n", mdatalen));
}
--
Dmitry
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