From nobody Thu Dec 18 05:17:32 2025 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 DBB0B179AE; Thu, 22 Aug 2024 02:40:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724294439; cv=none; b=WltncIA0XEdRKHb7IyjEISQdFhpmnhK6DW1//zLe0TltQF4hdFaE1tNIhdlUAC+PGAgX+0nlxhw5YSqlbIwi8SEZkgf456Vn6DjuoU0AH/TDb54iEc6WzY6Fb8iVHwZ/OxIFSObZjzChLQxiTSNv0Uj0HfmMCyogynEeoKQvfaI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724294439; c=relaxed/simple; bh=+ePuMzWc2Yl3+3iLStTY13rGvPwCXwZFagTUpN3LkOs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=oJaPeGtMi6NUW05x3I1YtJr8yfCnZewRh/11AudJVxOnOnQikG53B/e/EB00E2kJ8atB6wBUlPHuK5pCh1Jge4VBfZQRA/A90Bsj3IRFQT7u/LcEnAiOpQJu6AtrqLP8uhPO0nuFM1k6KGTSlOuZqL6qwijMU/+DDZIHQig5IBM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Wq6r82XXnz4f3jtC; Thu, 22 Aug 2024 10:40:24 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 0D8A11A0568; Thu, 22 Aug 2024 10:40:34 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgCHr4UapcZmqbd1CQ--.38129S10; Thu, 22 Aug 2024 10:40:33 +0800 (CST) From: libaokun@huaweicloud.com To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, ritesh.list@gmail.com, ojaswin@linux.ibm.com, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, libaokun@huaweicloud.com, Baokun Li , stable@kernel.org Subject: [PATCH v2 06/25] ext4: aovid use-after-free in ext4_ext_insert_extent() Date: Thu, 22 Aug 2024 10:35:26 +0800 Message-Id: <20240822023545.1994557-7-libaokun@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240822023545.1994557-1-libaokun@huaweicloud.com> References: <20240822023545.1994557-1-libaokun@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: gCh0CgCHr4UapcZmqbd1CQ--.38129S10 X-Coremail-Antispam: 1UD129KBjvJXoW7tF4DAF4rJw48JF1kCF4kJFb_yoW5JFy5pr 1DCryxGr1Yq34UKrWDJa1UZr1xK3WUGa1UJryfGrW29FyUJry8WF97tF1jyFyDWFW8ZFy5 ZF48tryUJw17Ka7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQY14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwAKzVCY07xG64k0F24lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l 4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67 AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8I cVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY6xAIw20EY4 v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AK xVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUbT7KDUUUUU== X-CM-SenderInfo: 5olet0hnxqqx5xdzvxpfor3voofrz/1tbiAgADBWbFpZhEFQAAsL Content-Type: text/plain; charset="utf-8" From: Baokun Li 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 =3D *ppath =3D 2000 ext4_ext_create_new_leaf(ppath) ext4_find_extent(ppath) path =3D *ppath =3D 2000 if (depth > path[0].p_maxdepth) kfree(path =3D 2000); *ppath =3D path =3D NULL; path =3D kcalloc() =3D 3000 *ppath =3D 3000; return path; /* here path is still 2000, UAF! */ eh =3D path[depth].p_hdr =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D 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 [...] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D 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-a8= 5c-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 --- fs/ext4/extents.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 5879aef159d8..91c6586afcca 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2116,6 +2116,7 @@ int ext4_ext_insert_extent(handle_t *handle, struct i= node *inode, ppath, newext); if (err) goto cleanup; + path =3D *ppath; depth =3D ext_depth(inode); eh =3D path[depth].p_hdr; =20 --=20 2.39.2