From nobody Thu Apr 9 10:31:46 2026 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 AE18CC433FE for ; Thu, 20 Oct 2022 22:36:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229691AbiJTWgl (ORCPT ); Thu, 20 Oct 2022 18:36:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229452AbiJTWgh (ORCPT ); Thu, 20 Oct 2022 18:36:37 -0400 Received: from p3plwbeout15-02.prod.phx3.secureserver.net (p3plsmtp15-02-2.prod.phx3.secureserver.net [173.201.193.36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E50351C2098 for ; Thu, 20 Oct 2022 15:36:35 -0700 (PDT) Received: from mailex.mailcore.me ([94.136.40.142]) by :WBEOUT: with ESMTP id le9SozUdUgJnvle9ToDIXy; Thu, 20 Oct 2022 15:36:35 -0700 X-CMAE-Analysis: v=2.4 cv=WcXJ12tX c=1 sm=1 tr=0 ts=6351cd73 a=s1hRAmXuQnGNrIj+3lWWVA==:117 a=84ok6UeoqCVsigPHarzEiQ==:17 a=ggZhUymU-5wA:10 a=Qawa6l4ZSaYA:10 a=VwQbUJbxAAAA:8 a=gQ9z1Vi_AAAA:8 a=pGLkceISAAAA:8 a=FXvPX3liAAAA:8 a=LyTzotujRfjnjsB5pxYA:9 a=AjGcO6oz07-iQ99wixmX:22 a=TvPxYD56syJNzSX8U-5E:22 a=UObqyxdv-6Yh2QiB9mM_:22 X-SECURESERVER-ACCT: phillip@squashfs.org.uk X-SID: le9SozUdUgJnv Received: from 82-69-79-175.dsl.in-addr.zen.co.uk ([82.69.79.175] helo=phoenix.fritz.box) by smtp12.mailcore.me with esmtpa (Exim 4.94.2) (envelope-from ) id 1ole9R-0006zQ-Bl; Thu, 20 Oct 2022 23:36:33 +0100 From: Phillip Lougher To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: hsinyi@chromium.org, regressions@leemhuis.info, regressions@lists.linux.dev, dimitri.ledkov@canonical.com, michael.vogt@canonical.com, phillip.lougher@gmail.com, ogra@ubuntu.com, olivier.tilloy@canonical.com, Phillip Lougher , Mirsad Goran Todorovac , Slade Watkins , Bagas Sanjaya , stable@vger.kernel.org Subject: [PATCH 1/3] squashfs: fix read regression introduced in readahead code Date: Thu, 20 Oct 2022 23:36:14 +0100 Message-Id: <20221020223616.7571-2-phillip@squashfs.org.uk> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221020223616.7571-1-phillip@squashfs.org.uk> References: <20221020223616.7571-1-phillip@squashfs.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailcore-Auth: 439999529 X-Mailcore-Domain: 1394945 X-123-reg-Authenticated: phillip@squashfs.org.uk X-Originating-IP: 82.69.79.175 X-CMAE-Envelope: MS4xfKZBdbxZBAoNqPHqI9NuRzl+GOzyCWZQCO6ZXbv/hiCUtlX8MY+jpDmRVuRF27M6mavTBLBRTrH+BRFIglHVQP7WN7LJlzpoyXcZIOBD9KtAFfC9O1Se 60IbC4/w87Exglg/XTwxVyjasd7T58HLQyS8laZDUAq7aFYbjD+soa5fZvmY7Gd2o8qn8uA8FKkB1DfyfWQKvZC+Hv2kAKCxWA+pt/hkBRVJyMLBaNUreDYX LgQzZT0lUu7qy43yvhMDVQ== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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. Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Link: https://lore.kernel.org/lkml/b0c258c3-6dcf-aade-efc4-d62a8b3a1ce2@alu= .unizg.hr/ Reported-by: Mirsad Goran Todorovac Tested-by: Mirsad Goran Todorovac Tested-by: Slade Watkins Tested-by: Bagas Sanjaya Cc: Signed-off-by: Phillip Lougher --- fs/squashfs/file.c | 7 ++++--- fs/squashfs/page_actor.c | 3 +++ fs/squashfs/page_actor.h | 6 +++++- 3 files changed, 12 insertions(+), 4 deletions(-) diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c index e56510964b22..e526eb7a1658 100644 --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -557,6 +557,7 @@ static void squashfs_readahead(struct readahead_control= *ractl) int res, bsize; u64 block =3D 0; unsigned int expected; + struct page *last_page; =20 nr_pages =3D __readahead_batch(ractl, pages, max_pages); if (!nr_pages) @@ -593,15 +594,15 @@ static void squashfs_readahead(struct readahead_contr= ol *ractl) =20 res =3D squashfs_read_data(inode->i_sb, block, bsize, NULL, actor); =20 - squashfs_page_actor_free(actor); + last_page =3D squashfs_page_actor_free(actor); =20 if (res =3D=3D expected) { int bytes; =20 /* Last page (if present) may have trailing bytes not filled */ bytes =3D res % PAGE_SIZE; - if (pages[nr_pages - 1]->index =3D=3D file_end && bytes) - memzero_page(pages[nr_pages - 1], bytes, + if (index =3D=3D file_end && bytes && last_page) + memzero_page(last_page, bytes, PAGE_SIZE - bytes); =20 for (i =3D 0; i < nr_pages; i++) { diff --git a/fs/squashfs/page_actor.c b/fs/squashfs/page_actor.c index 54b93bf4a25c..81af6c4ca115 100644 --- a/fs/squashfs/page_actor.c +++ b/fs/squashfs/page_actor.c @@ -71,11 +71,13 @@ static void *handle_next_page(struct squashfs_page_acto= r *actor) (actor->next_index !=3D actor->page[actor->next_page]->index)) { actor->next_index++; actor->returned_pages++; + actor->last_page =3D NULL; return actor->alloc_buffer ? actor->tmp_buffer : ERR_PTR(-ENOMEM); } =20 actor->next_index++; actor->returned_pages++; + actor->last_page =3D actor->page[actor->next_page]; return actor->pageaddr =3D kmap_local_page(actor->page[actor->next_page++= ]); } =20 @@ -125,6 +127,7 @@ struct squashfs_page_actor *squashfs_page_actor_init_sp= ecial(struct squashfs_sb_ actor->returned_pages =3D 0; actor->next_index =3D page[0]->index & ~((1 << (msblk->block_log - PAGE_S= HIFT)) - 1); actor->pageaddr =3D NULL; + actor->last_page =3D NULL; actor->alloc_buffer =3D msblk->decompressor->alloc_buffer; actor->squashfs_first_page =3D direct_first_page; actor->squashfs_next_page =3D direct_next_page; diff --git a/fs/squashfs/page_actor.h b/fs/squashfs/page_actor.h index 95ffbb543d91..97d4983559b1 100644 --- 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 *squashfs_page_actor_= init(void **buffer, 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 *ac= tor) +static inline struct page *squashfs_page_actor_free(struct squashfs_page_a= ctor *actor) { + struct page *last_page =3D actor->last_page; + kfree(actor->tmp_buffer); kfree(actor); + return last_page; } static inline void *squashfs_first_page(struct squashfs_page_actor *actor) { --=20 2.35.1 From nobody Thu Apr 9 10:31:46 2026 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 B10EEC433FE for ; Thu, 20 Oct 2022 22:36:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229735AbiJTWgp (ORCPT ); Thu, 20 Oct 2022 18:36:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229697AbiJTWgm (ORCPT ); Thu, 20 Oct 2022 18:36:42 -0400 Received: from p3plwbeout18-05.prod.phx3.secureserver.net (p3plsmtp18-05-2.prod.phx3.secureserver.net [173.201.193.190]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A19FB208828 for ; Thu, 20 Oct 2022 15:36:40 -0700 (PDT) Received: from mailex.mailcore.me ([94.136.40.145]) by :WBEOUT: with ESMTP id le9XojAFew7vale9YoyLo6; Thu, 20 Oct 2022 15:36:40 -0700 X-CMAE-Analysis: v=2.4 cv=f5eNuM+M c=1 sm=1 tr=0 ts=6351cd78 a=7e6w4QD8YWtpVJ/7+iiidw==:117 a=84ok6UeoqCVsigPHarzEiQ==:17 a=ggZhUymU-5wA:10 a=Qawa6l4ZSaYA:10 a=FXvPX3liAAAA:8 a=VwQbUJbxAAAA:8 a=z1XB94rXoAV2oHx9HPIA:9 a=UObqyxdv-6Yh2QiB9mM_:22 a=AjGcO6oz07-iQ99wixmX:22 X-SECURESERVER-ACCT: phillip@squashfs.org.uk X-SID: le9XojAFew7va Received: from 82-69-79-175.dsl.in-addr.zen.co.uk ([82.69.79.175] helo=phoenix.fritz.box) by smtp12.mailcore.me with esmtpa (Exim 4.94.2) (envelope-from ) id 1ole9W-0006zQ-Jd; Thu, 20 Oct 2022 23:36:38 +0100 From: Phillip Lougher To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: hsinyi@chromium.org, regressions@leemhuis.info, regressions@lists.linux.dev, dimitri.ledkov@canonical.com, michael.vogt@canonical.com, phillip.lougher@gmail.com, ogra@ubuntu.com, olivier.tilloy@canonical.com, Phillip Lougher , stable@vger.kernel.org Subject: [PATCH 2/3] squashfs: fix extending readahead beyond end of file Date: Thu, 20 Oct 2022 23:36:15 +0100 Message-Id: <20221020223616.7571-3-phillip@squashfs.org.uk> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221020223616.7571-1-phillip@squashfs.org.uk> References: <20221020223616.7571-1-phillip@squashfs.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailcore-Auth: 439999529 X-Mailcore-Domain: 1394945 X-123-reg-Authenticated: phillip@squashfs.org.uk X-Originating-IP: 82.69.79.175 X-CMAE-Envelope: MS4xfLVqZTEL6y7WsBl/SilQq+U1I+1q4XI20YGsxlSG6b6FvIDoNoiBLvr05x4IIAc/kR2HNK4sLo6vrmVcrjy5dV+7dIO+qm/RXszzjmVbMt2lTGdGRXkt +S4wdVtVa/HvyQDkUxjhOraK7i8NuQbTctmdMwT7yl5whWtsElFhZ85ctsMi7jMtpt5DLuWxEhqqNakxtLBqZdx1X6f50IyoalsrllYkslRC3u3gzuOKpBsh I9ugfyuiK3q9ok9o873C6A== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The readahead code will try to extend readahead to the entire size of the Squashfs data block. But, it didn't take into account that the last block at the end of the file may not be a whole block. In this case, the code would extend readahead to beyond the end of the file, leaving trailing pages. Fix this by only requesting the expected number of pages. Fixes: 8fc78b6fe24c ("squashfs: implement readahead") Signed-off-by: Phillip Lougher Cc: Tested-by: Bagas Sanjaya --- fs/squashfs/file.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c index e526eb7a1658..f0afd4d6fd30 100644 --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -559,6 +559,12 @@ static void squashfs_readahead(struct readahead_contro= l *ractl) unsigned int expected; struct page *last_page; =20 + expected =3D start >> msblk->block_log =3D=3D file_end ? + (i_size_read(inode) & (msblk->block_size - 1)) : + msblk->block_size; + + max_pages =3D (expected + PAGE_SIZE - 1) >> PAGE_SHIFT; + nr_pages =3D __readahead_batch(ractl, pages, max_pages); if (!nr_pages) break; @@ -567,13 +573,10 @@ static void squashfs_readahead(struct readahead_contr= ol *ractl) goto skip_pages; =20 index =3D pages[0]->index >> shift; + if ((pages[nr_pages - 1]->index >> shift) !=3D index) goto skip_pages; =20 - expected =3D index =3D=3D file_end ? - (i_size_read(inode) & (msblk->block_size - 1)) : - msblk->block_size; - if (index =3D=3D file_end && squashfs_i(inode)->fragment_block !=3D SQUASHFS_INVALID_BLK) { res =3D squashfs_readahead_fragment(pages, nr_pages, --=20 2.35.1 From nobody Thu Apr 9 10:31:46 2026 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 E633FC433FE for ; Thu, 20 Oct 2022 22:36:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229777AbiJTWgt (ORCPT ); Thu, 20 Oct 2022 18:36:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229740AbiJTWgq (ORCPT ); Thu, 20 Oct 2022 18:36:46 -0400 Received: from p3plwbeout22-02.prod.phx3.secureserver.net (p3plsmtp22-02-2.prod.phx3.secureserver.net [68.178.252.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3099C222F1C for ; Thu, 20 Oct 2022 15:36:44 -0700 (PDT) Received: from mailex.mailcore.me ([94.136.40.144]) by :WBEOUT: with ESMTP id le9aojCr1imR6le9bos5ab; Thu, 20 Oct 2022 15:36:43 -0700 X-CMAE-Analysis: v=2.4 cv=U/ZXscnu c=1 sm=1 tr=0 ts=6351cd7b a=wXHyRMViKMYRd//SnbHIqA==:117 a=84ok6UeoqCVsigPHarzEiQ==:17 a=ggZhUymU-5wA:10 a=Qawa6l4ZSaYA:10 a=VwQbUJbxAAAA:8 a=FXvPX3liAAAA:8 a=NzQU21p7aw8KqXuY42AA:9 a=AjGcO6oz07-iQ99wixmX:22 a=UObqyxdv-6Yh2QiB9mM_:22 X-SECURESERVER-ACCT: phillip@squashfs.org.uk X-SID: le9aojCr1imR6 Received: from 82-69-79-175.dsl.in-addr.zen.co.uk ([82.69.79.175] helo=phoenix.fritz.box) by smtp12.mailcore.me with esmtpa (Exim 4.94.2) (envelope-from ) id 1ole9Z-0006zQ-Oa; Thu, 20 Oct 2022 23:36:42 +0100 From: Phillip Lougher To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: hsinyi@chromium.org, regressions@leemhuis.info, regressions@lists.linux.dev, dimitri.ledkov@canonical.com, michael.vogt@canonical.com, phillip.lougher@gmail.com, ogra@ubuntu.com, olivier.tilloy@canonical.com, Phillip Lougher , stable@vger.kernel.org Subject: [PATCH 3/3] squashfs: fix buffer release race condition in readahead code Date: Thu, 20 Oct 2022 23:36:16 +0100 Message-Id: <20221020223616.7571-4-phillip@squashfs.org.uk> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221020223616.7571-1-phillip@squashfs.org.uk> References: <20221020223616.7571-1-phillip@squashfs.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailcore-Auth: 439999529 X-Mailcore-Domain: 1394945 X-123-reg-Authenticated: phillip@squashfs.org.uk X-Originating-IP: 82.69.79.175 X-CMAE-Envelope: MS4xfAeCv/9N9gGLkcg1ImRY2fUmkVE71wOfuWJmX1a0UkB/ryWiX3y5yIue4/Yy3QtFRpidgVVBo22XNLG+TfnbBSVH3gJLNbtv2eP7vlZRmcpl5Gej0pr+ t7+OhBCF8T08Ib1MYoekZGQEHIEufT3c0Iya0RdaNxWE5uTEpCgSF7zgj8HfU0GeU0ICZLb2Gv+oMq0TDRZ57BXmGYbxUQ3b/FFpLNP/q/bsh7kGsn/mHo0T 3XjQ/9k2IJxEO2w5nvW+zA== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Fix a buffer release race condition, where the error value was used after release. Fixes: b09a7a036d20 ("squashfs: support reading fragments in readahead call= ") Cc: Signed-off-by: Phillip Lougher Tested-by: Bagas Sanjaya --- fs/squashfs/file.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c index f0afd4d6fd30..8ba8c4c50770 100644 --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -506,8 +506,9 @@ static int squashfs_readahead_fragment(struct page **pa= ge, squashfs_i(inode)->fragment_size); struct squashfs_sb_info *msblk =3D inode->i_sb->s_fs_info; unsigned int n, mask =3D (1 << (msblk->block_log - PAGE_SHIFT)) - 1; + int error =3D buffer->error; =20 - if (buffer->error) + if (error) goto out; =20 expected +=3D squashfs_i(inode)->fragment_offset; @@ -529,7 +530,7 @@ static int squashfs_readahead_fragment(struct page **pa= ge, =20 out: squashfs_cache_put(buffer); - return buffer->error; + return error; } =20 static void squashfs_readahead(struct readahead_control *ractl) --=20 2.35.1