From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97B2DC433FE for ; Wed, 2 Nov 2022 02:37:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230208AbiKBCh5 (ORCPT ); Tue, 1 Nov 2022 22:37:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229742AbiKBChy (ORCPT ); Tue, 1 Nov 2022 22:37:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 812911B1EF for ; Tue, 1 Nov 2022 19:37:46 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1C947617AD for ; Wed, 2 Nov 2022 02:37:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59979C433D7; Wed, 2 Nov 2022 02:37:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667356665; bh=i2d4y0pdHZmPNA5T+qYwUJyWrEbYTBbJDexJ9TWUkO4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F+GEgYlO5TMtqS36QzuTSvwSEZ8fwHCyNSYOubLa5JG2Yn3r/YG4uW+6UJD7HMT09 dtJuj/kAwwR4mrG3u6abMEqGZ7N0d4zmNSo38WGtvWu9R3Y3INzOTOvkVIv+PUUYCe z7bfQwMDm9APs+tYjyd4WZrcfFwgJ4KL0YQ1Ali0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Phillip Lougher , Mirsad Goran Todorovac , Slade Watkins , Bagas Sanjaya , Marc Miltenberger , Dimitri John Ledkov , Hsin-Yi Wang , Thorsten Leemhuis , Andrew Morton Subject: [PATCH 6.0 039/240] squashfs: fix read regression introduced in readahead code Date: Wed, 2 Nov 2022 03:30:14 +0100 Message-Id: <20221102022112.286973742@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221102022111.398283374@linuxfoundation.org> References: <20221102022111.398283374@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Phillip Lougher commit 9ef8eb6104527bfe9ed31f7a4ffa721390adf9a8 upstream. Patch series "squashfs: fix some regressions introduced in the readahead code". This patchset fixes 3 regressions introduced by the recent readahead code changes. The first regression is causing "snaps" to randomly fail after a couple of hours or days, which how the regression came to light. This patch (of 3): If a file isn't a whole multiple of the page size, the last page will have trailing bytes unfilled. There was a mistake in the readahead code which did this. In particular it incorrectly assumed that the last page in the readahead page array (page[nr_pages - 1]) will always contain the last page in the block, which if we're at file end, will be the page that needs to be zero filled. But the readahead code may not return the last page in the block, which means it is unmapped and will be skipped by the decompressors (a temporary buffer used). In this case the zero filling code will zero out the wrong page, leading to data corruption. Fix this by by extending the "page actor" to return the last page if present, or NULL if a temporary buffer was used. Link: https://lkml.kernel.org/r/20221020223616.7571-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20221020223616.7571-2-phillip@squashfs.org.uk Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Link: https://lore.kernel.org/lkml/b0c258c3-6dcf-aade-efc4-d62a8b3a1ce2@alu.unizg.hr/ Signed-off-by: Phillip Lougher Reported-by: Mirsad Goran Todorovac Tested-by: Mirsad Goran Todorovac Tested-by: Slade Watkins Tested-by: Bagas Sanjaya Reported-by: Marc Miltenberger Cc: Dimitri John Ledkov Cc: Hsin-Yi Wang Cc: Thorsten Leemhuis Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/squashfs/file.c | 7 ++++--- fs/squashfs/page_actor.c | 3 +++ fs/squashfs/page_actor.h | 6 +++++- 3 files changed, 12 insertions(+), 4 deletions(-) --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -557,6 +557,7 @@ static void squashfs_readahead(struct re int res, bsize; u64 block = 0; unsigned int expected; + struct page *last_page; nr_pages = __readahead_batch(ractl, pages, max_pages); if (!nr_pages) @@ -593,15 +594,15 @@ static void squashfs_readahead(struct re res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor); - squashfs_page_actor_free(actor); + last_page = squashfs_page_actor_free(actor); if (res == expected) { int bytes; /* Last page (if present) may have trailing bytes not filled */ bytes = res % PAGE_SIZE; - if (pages[nr_pages - 1]->index == file_end && bytes) - memzero_page(pages[nr_pages - 1], bytes, + if (index == file_end && bytes && last_page) + memzero_page(last_page, bytes, PAGE_SIZE - bytes); for (i = 0; i < nr_pages; i++) { --- a/fs/squashfs/page_actor.c +++ b/fs/squashfs/page_actor.c @@ -71,11 +71,13 @@ static void *handle_next_page(struct squ (actor->next_index != actor->page[actor->next_page]->index)) { actor->next_index++; actor->returned_pages++; + actor->last_page = NULL; return actor->alloc_buffer ? actor->tmp_buffer : ERR_PTR(-ENOMEM); } actor->next_index++; actor->returned_pages++; + actor->last_page = actor->page[actor->next_page]; return actor->pageaddr = kmap_local_page(actor->page[actor->next_page++]); } @@ -125,6 +127,7 @@ struct squashfs_page_actor *squashfs_pag actor->returned_pages = 0; actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1); actor->pageaddr = NULL; + actor->last_page = NULL; actor->alloc_buffer = msblk->decompressor->alloc_buffer; actor->squashfs_first_page = direct_first_page; actor->squashfs_next_page = direct_next_page; --- a/fs/squashfs/page_actor.h +++ b/fs/squashfs/page_actor.h @@ -16,6 +16,7 @@ struct squashfs_page_actor { void *(*squashfs_first_page)(struct squashfs_page_actor *); void *(*squashfs_next_page)(struct squashfs_page_actor *); void (*squashfs_finish_page)(struct squashfs_page_actor *); + struct page *last_page; int pages; int length; int next_page; @@ -29,10 +30,13 @@ extern struct squashfs_page_actor *squas extern struct squashfs_page_actor *squashfs_page_actor_init_special( struct squashfs_sb_info *msblk, struct page **page, int pages, int length); -static inline void squashfs_page_actor_free(struct squashfs_page_actor *actor) +static inline struct page *squashfs_page_actor_free(struct squashfs_page_actor *actor) { + struct page *last_page = actor->last_page; + kfree(actor->tmp_buffer); kfree(actor); + return last_page; } static inline void *squashfs_first_page(struct squashfs_page_actor *actor) {