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 D0F1A1C69D for ; Mon, 6 Jan 2025 16:21:24 +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=1736180484; cv=none; b=dRd6m0g+/GV3exFxHLlwjmIIpt33sfYCLMSVKystFfs8OsLs2HSP0v6S+RT0H4nJyZGPD7HfZLVruoGP4eueon9gDAkUNM4Yxratcad/jItPB7PBqo5zoUxXGI2fpplLC/Yb0o7sHhBfYzkOJxbd8Zq+SAYQyycKF5GtAg3Dd1o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736180484; c=relaxed/simple; bh=OnvtGORQCM8Dzc1epqmFvrhqNnsquD4ufau4a7XRT6A=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=tUADvjcqWDeA1UDq4GCpq0xKwYx8ffVLjO+IDvIeluFNamm6eBxsbaRWbETp6OVNExTL3w9u5FC76QlEDjO0Sxo0OcTPMwjdZDKOBUYwW7+jx9NKvfhPTKImKBIp07zmfC/LCzyMoGO8XJF9Q7731wZfoQ31Yvj79Y2MS+W9fKA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rEjBRI9l; 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="rEjBRI9l" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C806C4CED2; Mon, 6 Jan 2025 16:21:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1736180484; bh=OnvtGORQCM8Dzc1epqmFvrhqNnsquD4ufau4a7XRT6A=; h=From:To:Cc:Subject:Date:Reply-to:From; b=rEjBRI9lpqyQQ6w0RLk2VLuP4j2BbgC7JFZNJ7JciilRLRpUsw/yIOwdTMev6/Pgy fnBLxO/yUCPHyONVi4f54Zd+D1Kq9y292IF8LyVeqPFVJhdUR/JFMrlf9VrujLozx9 +ycwxU3oSEQIxVjCmB5PdPYzWImwpkwNfjXwTMPE= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2024-56759: btrfs: fix use-after-free when COWing tree bock and tracing is enabled Date: Mon, 6 Jan 2025 17:20:53 +0100 Message-ID: <2025010653-CVE-2024-56759-e46e@gregkh> X-Mailer: git-send-email 2.47.1 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=2806; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=OnvtGORQCM8Dzc1epqmFvrhqNnsquD4ufau4a7XRT6A=; b=owGbwMvMwCRo6H6F97bub03G02pJDOk1TM/0ZExlGKJVsmNSSn9PWHRNavazoGULfW2Ld224y vF3V+C/jlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjIvcsMC04f2iv/eMK2FRV9 cesVk6/KMMhZ+DPM088+f0lBVuS2R+2OlaHP3Gd7cKn8BAA= 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 when COWing tree bock and tracing is enabled When a COWing a tree block, at btrfs_cow_block(), and we have the tracepoint trace_btrfs_cow_block() enabled and preemption is also enabled (CONFIG_PREEMPT=y), we can trigger a use-after-free in the COWed extent buffer while inside the tracepoint code. This is because in some paths that call btrfs_cow_block(), such as btrfs_search_slot(), we are holding the last reference on the extent buffer @buf so btrfs_force_cow_block() drops the last reference on the @buf extent buffer when it calls free_extent_buffer_stale(buf), which schedules the release of the extent buffer with RCU. This means that if we are on a kernel with preemption, the current task may be preempted before calling trace_btrfs_cow_block() and the extent buffer already released by the time trace_btrfs_cow_block() is called, resulting in a use-after-free. Fix this by moving the trace_btrfs_cow_block() from btrfs_cow_block() to btrfs_force_cow_block() before the COWed extent buffer is freed. This also has a side effect of invoking the tracepoint in the tree defrag code, at defrag.c:btrfs_realloc_node(), since btrfs_force_cow_block() is called there, but this is fine and it was actually missing there. The Linux kernel CVE team has assigned CVE-2024-56759 to this issue. Affected and fixed versions =========================== Fixed in 6.12.8 with commit c3a403d8ce36f5a809a492581de5ad17843e4701 Fixed in 6.13-rc5 with commit 44f52bbe96dfdbe4aca3818a2534520082a07040 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-2024-56759 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/ctree.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/c3a403d8ce36f5a809a492581de5ad17843e4701 https://git.kernel.org/stable/c/44f52bbe96dfdbe4aca3818a2534520082a07040