Messages in this thread | | | Date | Fri, 28 Nov 2008 11:27:45 +0000 | From | Al Viro <> | Subject | Re: [RFC v10][PATCH 09/13] Restore open file descriprtors |
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On Wed, Nov 26, 2008 at 08:04:40PM -0500, Oren Laadan wrote:
> +/** > + * cr_attach_get_file - attach (and get) lonely file ptr to a file descriptor > + * @file: lonely file pointer > + */ > +static int cr_attach_get_file(struct file *file) > +{ > + int fd = get_unused_fd_flags(0); > + > + if (fd >= 0) { > + fsnotify_open(file->f_path.dentry); > + fd_install(fd, file); > + get_file(file); > + } > + return fd; > +}
What happens if another thread closes the descriptor in question between fd_install() and get_file()?
> + fd = cr_attach_file(file); /* no need to cleanup 'file' below */ > + if (fd < 0) { > + filp_close(file, NULL); > + ret = fd; > + goto out; > + } > + > + /* register new <objref, file> tuple in hash table */ > + ret = cr_obj_add_ref(ctx, file, parent, CR_OBJ_FILE, 0); > + if (ret < 0) > + goto out;
Who said that file still exists at that point?
BTW, there are shitloads of races here - references to fd and struct file * are mixed in a way that breaks *badly* if descriptor table is played with by another thread.
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