From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4556442902A for ; Thu, 3 Sep 2026 08:22:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788423763; cv=none; b=MTWwcFG9QaTrDJ1zr5c9z39cl1jqa92PHk8mX6edtYuS+j8ZBZxCmRZoAFaNnu1qypNsGIl5RFMUGa/XJolR3167LKH4wjoHbgNrS/wuSZJL3JB5fVeDbmijtNArpuqSX/HGVMwtTUUKsr+lUUcSMTn14/xWXtxMbKVYujkhDls= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788423763; c=relaxed/simple; bh=GgjilJjtfiHtD9wFuanRNxQd5ENwaMESMZAYE5khIAk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=eUt7GrIFmQjipFGby3CRlHskn0HZgB4b2W3cPMYr58/v361cx2BhDMEEesne377D0k/vY4o4JSzrTUBA/EPTwndBoZpPlYdzrfem3LHjchGBQgJ3J+0js5RbkS73kzarHZZX7WKJVcNT/cXP33mTW3BEWHEsKXCLL7r6ncBSazc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0AxnH863; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0AxnH863" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 528601F00A3D; Thu, 3 Sep 2026 08:22:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788423761; bh=bHxlcgz0FCRRYVuhF5aQKA9hS65CyUr6PPJEExztHhU=; h=From:To:Cc:Subject:Date:Reply-To; b=0AxnH863jJDGogJRYxo/8z7lMX2O0+dMpqtuFqWUEx8qMjbLI8VgZCAL769pAwsMn e2DMyHcd5RZOQgRIrsaD3hjqhvNWvfbjMihi3y286+AItuXvQkSTfTEqMYQM7hK0H2 1E5cTLYqn7lQ4o2Asa4BjPhJ+Zqaqu6hJldEaEyk= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-80734: btrfs: initialize inode mapping flags for cached inodes Date: Thu, 3 Sep 2026 10:22:03 +0200 Message-ID: <2026090358-CVE-2026-80734-7f7d@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5425; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=FokjKTYfCwMrD6YOAoIi06H/2viYJwXdYd2341r3dr4=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkz9dQy5+l9nvJLYbvUxpSU7xeO8S8M/eSw7Nm5Q3YTt Nj8uU/zdMSyMAgyMciKKbJ82cZzdH/FIUUvQ9vTMHNYmUCGMHBxCsBE9v5lWND4tls//el0Le8t B257F6y3jz3QuYBhfrg9u4Lvr7OfupK9dPwzfM+LPVnHDgA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: btrfs: initialize inode mapping flags for cached inodes [BUG] When running generic/795 with 8K block size, 4K page size, the test always fails, triggering some ASSERT()s related to folio size: 795 (241074): drop_caches: 3 assertion failed: IS_ALIGNED(start, blocksize) && IS_ALIGNED(end + 1, blocksize), in extent_io.c:1404 (blocksize=8192 root=262 ino=258 start=16826368 end=16830463 mapping min order=0) ------------[ cut here ]------------ kernel BUG at extent_io.c:1404! Oops: invalid opcode: 0000 [#1] SMP CPU: 8 UID: 0 PID: 241105 Comm: fsstress Tainted: G OE 7.2.0-rc5-custom+ #442 PREEMPT(full) f4bfb352566f3949f29c233ce6f735050a03b245 Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:assert_folio_range.cold+0x3d/0x3f [btrfs] Call Trace: btrfs_read_folio+0x9e/0x170 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] prepare_one_folio.constprop.0+0x104/0x2a0 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] btrfs_buffered_write+0x285/0xa50 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] btrfs_do_write_iter+0x1aa/0x210 [btrfs 4cd1dd93b341b8ef766643f9512f4a86259567a3] iter_file_splice_write+0x31a/0x540 direct_splice_actor+0x53/0x170 splice_direct_to_actor+0xe9/0x240 do_splice_direct+0x76/0xb0 vfs_copy_file_range+0x1fd/0x630 __x64_sys_copy_file_range+0xf9/0x220 do_syscall_64+0xe1/0x790 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ---[ end trace 0000000000000000 ]--- The ASSERT() itself is added by a later patch. The crash is triggered with that new debug patch, and without this fix. [CAUSE] In the above case, the start 16826368 is properly 8K aligned, but the end (16830463 + 1) is not 8K aligned. Furthermore the mapping's minimal folio order is 0, not the expected 1 for 8K block size with 4K page size. So this means some inodes do not have btrfs_set_inode_mapping_order() called on it. The missing btrfs_set_inode_mapping_order() call happens for cached inodes, through the following events: - btrfs_create_new_inode() called for inode X Which properly sets minimal folio order for the VFS inode. - btrfs_update_inode() called for inode X Which calls btrfs_delayed_update_inode() to create a delayed_node into root->delayed_nodes xarray. - Drop cache/memory pressure, evicting in-memory inode X Which evicted the inode X, but delayed_node is still in root->delayed_nodes for future reuse. - btrfs_iget() for inode X called again btrfs_iget() |- btrfs_iget_locked() | |- iget5_locked_rcu() | Which creates a new vfs_inode for btrfs, whose mapping still | has the minimal order as 0. | |- btrfs_read_locked_inode() |- btrfs_fill_inode() | |- btrfs_get_delayed_node() | Which found out the previous node, and use that delayed | node to initialize the new inode. | |- filled = true; |- if (filled) goto cache_index; Which skips the btrfs_update_inode_mapping_flags() and btrfs_set_inode_mapping_order() calls. So the inode still has minimal folio order set as 0, not the required 1. Thus later page cache read will get a folio whose size is smaller than block size, as the mapping has its minimal folio order set as 0 not 1, then trigger the ASSERT(). [FIX] Move the btrfs_update_inode_mapping_flags() and btrfs_set_inode_mapping_order() calls under cache_index label, so that the mapping flags and minimal folio order is always set no matter if we have a cached inode. The Linux kernel CVE team has assigned CVE-2026-80734 to this issue. Affected and fixed versions =========================== Issue introduced in 6.15 with commit ecde48a1a6b3256bd49db8780bf37556b157783c and fixed in 7.1.9 with commit 0d26249671171ab759cb4fdce673554a690fa655 Issue introduced in 6.15 with commit ecde48a1a6b3256bd49db8780bf37556b157783c and fixed in 7.2 with commit 0ef349734a93227b45f65fc50a3311d1cc5f03e9 Issue introduced in 6.14.6 with commit ae584726e6eddf6cfbe49b3f4a78b3197716b6f8 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-80734 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: fs/btrfs/inode.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/0d26249671171ab759cb4fdce673554a690fa655 https://git.kernel.org/stable/c/0ef349734a93227b45f65fc50a3311d1cc5f03e9