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 1DECA57898 for ; Wed, 17 Apr 2024 10:31:27 +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=1713349888; cv=none; b=IaMRMzxZQu5G3lstGqdli54q/dVYFp3lCzihPMs7zHSYPu8+qzF4Y+S+QW/ADQCVdaEJg0sBXJ9+ghR8mDonas+zSl8ZzRXFjAGKeHwIB17QfEhtbDd36pCuikq6/8Av7vt8oGLYjN05J/yijvWl4RCMb8aDtMkinhjWWf+HINg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713349888; c=relaxed/simple; bh=g70cOq4gJdna822fkSZwH7LxyYNdzRPZZbZ3YGp0hKE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=SJo6ICUlw9tf88RQtMBhh+8mRuJHbuhtlqXCuihxTbpdMEw32x0b923nbLKDv7h4S23f2nuh/xhuKIwRyypu0bar1u96Xs2hCdVxUTQONPEifGccceHBH+qaMGGnOA9itVHi7Dk4KqqwSUDMGphd4gCKVfDxNkED3xAwzSugbLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vg6eQu+z; 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="vg6eQu+z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B2EFC072AA; Wed, 17 Apr 2024 10:31:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1713349887; bh=g70cOq4gJdna822fkSZwH7LxyYNdzRPZZbZ3YGp0hKE=; h=From:To:Cc:Subject:Date:Reply-to:From; b=vg6eQu+zHf/Op6lS171xgZhWMwRZQG1Rrr9wWH9cnnBM/KTLwInk6w69IGnASIYJ/ EBNf1kuiKh0pzEjWariD0B8H792L6Tok9i3WxiKUEjAa+D49EdVlFyEv18/d9dJq1+ KfsbukrWmBfBF7PG8p9++6BPklPFE/aW/PPNVBpM= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2024-26904: btrfs: fix data race at btrfs_use_block_rsv() when accessing block reserve Date: Wed, 17 Apr 2024 12:29:19 +0200 Message-ID: <2024041746-CVE-2024-26904-e3a8@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=4196; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=g70cOq4gJdna822fkSZwH7LxyYNdzRPZZbZ3YGp0hKE=; b=owGbwMvMwCRo6H6F97bub03G02pJDGnyS+IubnbwLdO9UMQ0+ZhTdlvxlgLl3KSQ3gXq2YFPf +RJvVjQEcvCIMjEICumyPJlG8/R/RWHFL0MbU/DzGFlAhnCwMUpABNRymSYX2fINrVIY3JpWspV y7Wq0pK5Jw/7MCy43pvpXdO3uLjp3ItEXc47u/yYxA4BAA== 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 race at btrfs_use_block_rsv() when accessing block reserve At btrfs_use_block_rsv() we read the size of a block reserve without locking its spinlock, which makes KCSAN complain because the size of a block reserve is always updated while holding its spinlock. The report from KCSAN is the following: [653.313148] BUG: KCSAN: data-race in btrfs_update_delayed_refs_rsv [btrfs] / btrfs_use_block_rsv [btrfs] [653.314755] read to 0x000000017f5871b8 of 8 bytes by task 7519 on cpu 0: [653.314779] btrfs_use_block_rsv+0xe4/0x2f8 [btrfs] [653.315606] btrfs_alloc_tree_block+0xdc/0x998 [btrfs] [653.316421] btrfs_force_cow_block+0x220/0xe38 [btrfs] [653.317242] btrfs_cow_block+0x1ac/0x568 [btrfs] [653.318060] btrfs_search_slot+0xda2/0x19b8 [btrfs] [653.318879] btrfs_del_csums+0x1dc/0x798 [btrfs] [653.319702] __btrfs_free_extent.isra.0+0xc24/0x2028 [btrfs] [653.320538] __btrfs_run_delayed_refs+0xd3c/0x2390 [btrfs] [653.321340] btrfs_run_delayed_refs+0xae/0x290 [btrfs] [653.322140] flush_space+0x5e4/0x718 [btrfs] [653.322958] btrfs_preempt_reclaim_metadata_space+0x102/0x2f8 [btrfs] [653.323781] process_one_work+0x3b6/0x838 [653.323800] worker_thread+0x75e/0xb10 [653.323817] kthread+0x21a/0x230 [653.323836] __ret_from_fork+0x6c/0xb8 [653.323855] ret_from_fork+0xa/0x30 [653.323887] write to 0x000000017f5871b8 of 8 bytes by task 576 on cpu 3: [653.323906] btrfs_update_delayed_refs_rsv+0x1a4/0x250 [btrfs] [653.324699] btrfs_add_delayed_data_ref+0x468/0x6d8 [btrfs] [653.325494] btrfs_free_extent+0x76/0x120 [btrfs] [653.326280] __btrfs_mod_ref+0x6a8/0x6b8 [btrfs] [653.327064] btrfs_dec_ref+0x50/0x70 [btrfs] [653.327849] walk_up_proc+0x236/0xa50 [btrfs] [653.328633] walk_up_tree+0x21c/0x448 [btrfs] [653.329418] btrfs_drop_snapshot+0x802/0x1328 [btrfs] [653.330205] btrfs_clean_one_deleted_snapshot+0x184/0x238 [btrfs] [653.330995] cleaner_kthread+0x2b0/0x2f0 [btrfs] [653.331781] kthread+0x21a/0x230 [653.331800] __ret_from_fork+0x6c/0xb8 [653.331818] ret_from_fork+0xa/0x30 So add a helper to get the size of a block reserve while holding the lock. 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-2024-26904 to this issue. Affected and fixed versions =========================== Fixed in 5.4.273 with commit 2daa2a8e895e Fixed in 6.1.83 with commit ab1be3f1aa77 Fixed in 6.6.23 with commit f6d4d29a1265 Fixed in 6.7.11 with commit 7e9422d35d57 Fixed in 6.8 with commit c7bb26b847e5 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-2024-26904 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.c fs/btrfs/block-rsv.h 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/2daa2a8e895e6dc2395f8628c011bcf1e019040d https://git.kernel.org/stable/c/ab1be3f1aa7799f99155488c28eacaef65eb68fb https://git.kernel.org/stable/c/f6d4d29a12655b42a13cec038c2902bb7efc50ed https://git.kernel.org/stable/c/7e9422d35d574b646269ca46010a835ca074b310 https://git.kernel.org/stable/c/c7bb26b847e5b97814f522686068c5628e2b3646