From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C48E313D25A for ; Wed, 17 Apr 2024 10:31:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713349872; cv=none; b=r0tTpOHo2jfPiV6ycU48F742P+qavsokojUeqpv3+0e/sQ+rbwuJ5HGVVZZYukUodDVdvr2N6n1EECvldIg7u3IHrjwH2DxQb9HmxAr13o0iT1lYFx7R4GP1nqqvDkuuFrRG6TKqYGsVBFVNL3E+ogOlzRpGh56jzu2IRXvq3Zc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713349872; c=relaxed/simple; bh=UCUr6Dl7CwKKt6nlGedDd0GZ+f0PFUytCmhbh8azvpA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=bx7nwxePwvUUUw1lFD/JgOwewI/Uht9sV/WQgmjjbVADbonB53Irt3as2fMbwxm7MxSZdccx/kXY6lZQUNye24i8GkY/8IeNm4IYEOjGJeb/fa/8jJN7XL/tTrQR5PUKsJELPxNV/HK20o+kNKGvmUyIG+1bwzsaOGCTA4RmNhQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=f6dAh6j/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="f6dAh6j/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5211C072AA; Wed, 17 Apr 2024 10:31:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1713349872; bh=UCUr6Dl7CwKKt6nlGedDd0GZ+f0PFUytCmhbh8azvpA=; h=From:To:Cc:Subject:Date:Reply-to:From; b=f6dAh6j/LAMtgzARP1L8njqf7PbOlh/9BfyHJmaJ74A1jCL/GPcqNKwz8+XUT8hYU +yRx7nuYdj4yQbN8O1txRRlahO3UGR9jlPKJIuCRs3au6m5MIwAURhfqRB5cdC3RJb CvI22U3xPu/YweyZ7HZqScXkYsGyYQCRKlO9c1Us= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2024-26905: btrfs: fix data races when accessing the reserved amount of block reserves Date: Wed, 17 Apr 2024 12:29:20 +0200 Message-ID: <2024041746-CVE-2024-26905-69f0@gregkh> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Reply-to: , X-Developer-Signature: v=1; a=openpgp-sha256; l=4207; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=UCUr6Dl7CwKKt6nlGedDd0GZ+f0PFUytCmhbh8azvpA=; b=owGbwMvMwCRo6H6F97bub03G02pJDGnyS+I2nvUOK93ovH4p14UZU2dv8q+V4xTU+iYh3bLgC PO50+KvO2JZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAi6/MYFhxfvEH64/Gsl7sc Hys07Ffc+9ORwYdhrkDNqoeOM3X+xqmlirzztZo+zWl+OQA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit Description =========== In the Linux kernel, the following vulnerability has been resolved: btrfs: fix data races when accessing the reserved amount of block reserves At space_info.c we have several places where we access the ->reserved field of a block reserve without taking the block reserve's spinlock first, which makes KCSAN warn about a data race since that field is always updated while holding the spinlock. The reports from KCSAN are like the following: [117.193526] BUG: KCSAN: data-race in btrfs_block_rsv_release [btrfs] / need_preemptive_reclaim [btrfs] [117.195148] read to 0x000000017f587190 of 8 bytes by task 6303 on cpu 3: [117.195172] need_preemptive_reclaim+0x222/0x2f0 [btrfs] [117.195992] __reserve_bytes+0xbb0/0xdc8 [btrfs] [117.196807] btrfs_reserve_metadata_bytes+0x4c/0x120 [btrfs] [117.197620] btrfs_block_rsv_add+0x78/0xa8 [btrfs] [117.198434] btrfs_delayed_update_inode+0x154/0x368 [btrfs] [117.199300] btrfs_update_inode+0x108/0x1c8 [btrfs] [117.200122] btrfs_dirty_inode+0xb4/0x140 [btrfs] [117.200937] btrfs_update_time+0x8c/0xb0 [btrfs] [117.201754] touch_atime+0x16c/0x1e0 [117.201789] filemap_read+0x674/0x728 [117.201823] btrfs_file_read_iter+0xf8/0x410 [btrfs] [117.202653] vfs_read+0x2b6/0x498 [117.203454] ksys_read+0xa2/0x150 [117.203473] __s390x_sys_read+0x68/0x88 [117.203495] do_syscall+0x1c6/0x210 [117.203517] __do_syscall+0xc8/0xf0 [117.203539] system_call+0x70/0x98 [117.203579] write to 0x000000017f587190 of 8 bytes by task 11 on cpu 0: [117.203604] btrfs_block_rsv_release+0x2e8/0x578 [btrfs] [117.204432] btrfs_delayed_inode_release_metadata+0x7c/0x1d0 [btrfs] [117.205259] __btrfs_update_delayed_inode+0x37c/0x5e0 [btrfs] [117.206093] btrfs_async_run_delayed_root+0x356/0x498 [btrfs] [117.206917] btrfs_work_helper+0x160/0x7a0 [btrfs] [117.207738] process_one_work+0x3b6/0x838 [117.207768] worker_thread+0x75e/0xb10 [117.207797] kthread+0x21a/0x230 [117.207830] __ret_from_fork+0x6c/0xb8 [117.207861] ret_from_fork+0xa/0x30 So add a helper to get the reserved amount of a block reserve while holding the lock. The value may be not be up to date anymore when used by need_preemptive_reclaim() and btrfs_preempt_reclaim_metadata_space(), but that's ok since the worst it can do is cause more reclaim work do be done sooner rather than later. Reading the field while holding the lock instead of using the data_race() annotation is used in order to prevent load tearing. The Linux kernel CVE team has assigned CVE-2024-26905 to this issue. Affected and fixed versions =========================== Fixed in 6.1.83 with commit 995e91c9556c Fixed in 6.6.23 with commit 82220b1835ba Fixed in 6.7.11 with commit c44542093525 Fixed in 6.8 with commit e06cc89475ed 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-2024-26905 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/block-rsv.h fs/btrfs/space-info.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/995e91c9556c8fc6028b474145a36e947d1eb6b6 https://git.kernel.org/stable/c/82220b1835baaebf4ae2e490f56353a341a09bd2 https://git.kernel.org/stable/c/c44542093525699a30c307dae1ea5a1b03b3302f https://git.kernel.org/stable/c/e06cc89475eddc1f3a7a4d471524256152c68166