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 E1B941AAE04 for ; Thu, 20 Jun 2024 11:16:56 +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=1718882217; cv=none; b=Mtllygm4ESyyqLEm0pHatKkKFum1a8rfY1/QAmMl7W+xIMSjZVn8olMufSO1c0h92fs1MMFNv7V8TuV3XnSQplLi+9cFrFeTHvMFwjt3mVGfB5hpcXvJb+rymBiWAlM7ZZrBlhcsDZXsurutdOYsjemMXep2Ml77SaVHY7ZzORU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718882217; c=relaxed/simple; bh=IvJBqu2pKBjRbX5ezXXLqsF7h1gI/BlsVzt45Q8RrN4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=OUQSHQRQp2TopPdTk1hw7hh+QVfyd/4jWlT8cE+ZJaaM0W3oVhqaYfdb3O68d79gJAypF8eSieMophqd3Q3iVPK9/lacZtBMxc6W1M69jRZMV1Q8/mTe9pziwrWh7RZyARglwzx5rfqh9ckJggcdtG0TiVpAokAK38hJDv1tXYE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Dr2wJjIn; 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="Dr2wJjIn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10A4AC2BD10; Thu, 20 Jun 2024 11:16:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718882216; bh=IvJBqu2pKBjRbX5ezXXLqsF7h1gI/BlsVzt45Q8RrN4=; h=From:To:Cc:Subject:Date:Reply-to:From; b=Dr2wJjInvJ0/xiCtse/ORNYz7k0CwGrsfkKDLIRwKVDAj9iukArAglARh5Jpm2bvA YjRWk4JiMH4Uh+V3KQHMaGasgsYC2LU6ogn0UycnvJXNQaPupYKCg00wFK7dCC1H+d zuFfFGYW6yp3uDC6ZkYI93YdkKSr9OdgEPBEfLBQ= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2022-48733: btrfs: fix use-after-free after failure to create a snapshot Date: Thu, 20 Jun 2024 13:16:13 +0200 Message-ID: <2024062000-CVE-2022-48733-4217@gregkh> X-Mailer: git-send-email 2.45.2 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=3477; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=IvJBqu2pKBjRbX5ezXXLqsF7h1gI/BlsVzt45Q8RrN4=; b=owGbwMvMwCRo6H6F97bub03G02pJDGkl/AW/nj/YnPv1/zKmU9INPlc/9S3e3sPspjqx70Jj+ WQLj9fBHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjCRaDuGuZIG118VNd1enufH o6T4905Cb9TGGQwLZnifevCqha+r3MPff+PF/fKTGz2qAA== 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 use-after-free after failure to create a snapshot At ioctl.c:create_snapshot(), we allocate a pending snapshot structure and then attach it to the transaction's list of pending snapshots. After that we call btrfs_commit_transaction(), and if that returns an error we jump to 'fail' label, where we kfree() the pending snapshot structure. This can result in a later use-after-free of the pending snapshot: 1) We allocated the pending snapshot and added it to the transaction's list of pending snapshots; 2) We call btrfs_commit_transaction(), and it fails either at the first call to btrfs_run_delayed_refs() or btrfs_start_dirty_block_groups(). In both cases, we don't abort the transaction and we release our transaction handle. We jump to the 'fail' label and free the pending snapshot structure. We return with the pending snapshot still in the transaction's list; 3) Another task commits the transaction. This time there's no error at all, and then during the transaction commit it accesses a pointer to the pending snapshot structure that the snapshot creation task has already freed, resulting in a user-after-free. This issue could actually be detected by smatch, which produced the following warning: fs/btrfs/ioctl.c:843 create_snapshot() warn: '&pending_snapshot->list' not removed from list So fix this by not having the snapshot creation ioctl directly add the pending snapshot to the transaction's list. Instead add the pending snapshot to the transaction handle, and then at btrfs_commit_transaction() we add the snapshot to the list only when we can guarantee that any error returned after that point will result in a transaction abort, in which case the ioctl code can safely free the pending snapshot and no one can access it anymore. The Linux kernel CVE team has assigned CVE-2022-48733 to this issue. Affected and fixed versions =========================== Fixed in 5.15.22 with commit a7b717fa1516 Fixed in 5.16.8 with commit 9372fa1d73da Fixed in 5.17 with commit 28b21c558a37 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-2022-48733 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/ioctl.c fs/btrfs/transaction.c fs/btrfs/transaction.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/a7b717fa15165d3d9245614680bebc48a52ac05d https://git.kernel.org/stable/c/9372fa1d73da5f1673921e365d0cd2c27ec7adc2 https://git.kernel.org/stable/c/28b21c558a3753171097193b6f6602a94169093a