From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:49202 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754905AbcBXDd2 (ORCPT ); Tue, 23 Feb 2016 22:33:28 -0500 Subject: Patch "fuse: break infinite loop in fuse_fill_write_pages()" has been added to the 3.10-stable tree To: klamm@yandex-team.ru, akpm@linux-foundation.org, gregkh@linuxfoundation.org, khlebnikov@yandex-team.ru, miklos@szeredi.hu, mpatlasov@parallels.com Cc: , From: Date: Tue, 23 Feb 2016 19:23:04 -0800 Message-ID: <145628418411643@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled fuse: break infinite loop in fuse_fill_write_pages() to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: fuse-break-infinite-loop-in-fuse_fill_write_pages.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 3ca8138f014a913f98e6ef40e939868e1e9ea876 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Mon, 12 Oct 2015 16:33:44 +0300 Subject: fuse: break infinite loop in fuse_fill_write_pages() From: Roman Gushchin commit 3ca8138f014a913f98e6ef40e939868e1e9ea876 upstream. I got a report about unkillable task eating CPU. Further investigation shows, that the problem is in the fuse_fill_write_pages() function. If iov's first segment has zero length, we get an infinite loop, because we never reach iov_iter_advance() call. Fix this by calling iov_iter_advance() before repeating an attempt to copy data from userspace. A similar problem is described in 124d3b7041f ("fix writev regression: pan hanging unkillable and un-straceable"). If zero-length segmend is followed by segment with invalid address, iov_iter_fault_in_readable() checks only first segment (zero-length), iov_iter_copy_from_user_atomic() skips it, fails at second and returns zero -> goto again without skipping zero-length segment. Patch calls iov_iter_advance() before goto again: we'll skip zero-length segment at second iteraction and iov_iter_fault_in_readable() will detect invalid address. Special thanks to Konstantin Khlebnikov, who helped a lot with the commit description. Cc: Andrew Morton Cc: Maxim Patlasov Cc: Konstantin Khlebnikov Signed-off-by: Roman Gushchin Signed-off-by: Miklos Szeredi Fixes: ea9b9907b82a ("fuse: implement perform_write") Signed-off-by: Greg Kroah-Hartman --- fs/fuse/file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -993,6 +993,7 @@ static ssize_t fuse_fill_write_pages(str mark_page_accessed(page); + iov_iter_advance(ii, tmp); if (!tmp) { unlock_page(page); page_cache_release(page); @@ -1005,7 +1006,6 @@ static ssize_t fuse_fill_write_pages(str req->page_descs[req->num_pages].length = tmp; req->num_pages++; - iov_iter_advance(ii, tmp); count += tmp; pos += tmp; offset += tmp; Patches currently in stable-queue which might be from klamm@yandex-team.ru are queue-3.10/fuse-break-infinite-loop-in-fuse_fill_write_pages.patch