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 6547B1922DB; Wed, 6 Nov 2024 12:15:59 +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=1730895359; cv=none; b=bDXRS/9Wf9GvXQfSVj/IzJs9R46cW9ThApgFQAiuf0yTWlI87spkpQX8w7BenIdF1L3qXqLA6k1KbBZVoKTc68OUlqMIsGTt1bZo5kr15+9lDzPicrN+Tp0+lcVdjLoFvvzEg7bC9zdks4PRWJt6qqbtnaqwz5IQo/ohKPof09M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730895359; c=relaxed/simple; bh=K28JGaKCgzSTdcTzisCw7nq/fPurKga+utzu26L0d1o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Yix237Whh7PRxBC5sZPCDBHVW7daM6csx7R/LTQY2ZIKNanTWWuXCa6krsu8HFRKMxUqPftzuyDZ7xZXMnoe9c2DouYpcFk55S+DzphzP9Uo8lK6huxF2rD9q0Kg+gGM2+f/XEfIYqOEF9hpxDWvTYiu/bnPTRfkvXKjczMmNHs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jRX23/vm; 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="jRX23/vm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD4FDC4CECD; Wed, 6 Nov 2024 12:15:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1730895359; bh=K28JGaKCgzSTdcTzisCw7nq/fPurKga+utzu26L0d1o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jRX23/vmaAN1m9s7oVDDzt7LiImQFZ+4OGlBStyp/Ly037aNJOouegiHnETIbK9Dd Np27oF8Ooy98OXiYf/1IthFs805minJN3EbKEa9zJJX6hgCjUjjgo+CexN7bh7SD95 iqghca3HmGGsTlOtjcnTJ5yxn0Zhp+XR6FzPxC04= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ojaswin Mujoo , stable@kernel.org, Baokun Li , Jan Kara , Theodore Tso Subject: [PATCH 4.19 191/350] ext4: aovid use-after-free in ext4_ext_insert_extent() Date: Wed, 6 Nov 2024 13:01:59 +0100 Message-ID: <20241106120325.679275104@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241106120320.865793091@linuxfoundation.org> References: <20241106120320.865793091@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Baokun Li commit a164f3a432aae62ca23d03e6d926b122ee5b860d upstream. As Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is reallocated in ext4_ext_create_new_leaf(), we'll use the stale path and cause UAF. Below is a sample trace with dummy values: ext4_ext_insert_extent path = *ppath = 2000 ext4_ext_create_new_leaf(ppath) ext4_find_extent(ppath) path = *ppath = 2000 if (depth > path[0].p_maxdepth) kfree(path = 2000); *ppath = path = NULL; path = kcalloc() = 3000 *ppath = 3000; return path; /* here path is still 2000, UAF! */ eh = path[depth].p_hdr ================================================================== BUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330 Read of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179 CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866 Call Trace: ext4_ext_insert_extent+0x26d4/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 [...] Allocated by task 179: ext4_find_extent+0x81c/0x1f70 ext4_ext_map_blocks+0x146/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] Freed by task 179: kfree+0xcb/0x240 ext4_find_extent+0x7c0/0x1f70 ext4_ext_insert_extent+0xa26/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] ================================================================== So use *ppath to update the path to avoid the above problem. Reported-by: Ojaswin Mujoo Closes: https://lore.kernel.org/r/ZqyL6rmtwl6N4MWR@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com Fixes: 10809df84a4d ("ext4: teach ext4_ext_find_extent() to realloc path if necessary") Cc: stable@kernel.org Signed-off-by: Baokun Li Reviewed-by: Jan Kara Link: https://patch.msgid.link/20240822023545.1994557-7-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/extents.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2099,6 +2099,7 @@ prepend: ppath, newext); if (err) goto cleanup; + path = *ppath; depth = ext_depth(inode); eh = path[depth].p_hdr;