From nobody Thu Dec 18 05:17:31 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 550F417BAF; Thu, 22 Aug 2024 02:40:35 +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=1724294438; cv=none; b=s7qcbu/wO820s4V28mkm3aoZhZyfGxkXaq+WnDys1vH+qtBADGq6DjTK69GWnIwPHCagXT//9FLUqhFgBlf2iYl7Uwocz9ielML/tKP6AfMx7kWns64vFZz4asqWVwPgCNAGOWXPbXH70Zni88qgSl6RuG87YDGTcPZkRczJsYc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724294438; c=relaxed/simple; bh=D4f8RzrBEfKrz258aXHXsrNd6G/zUq8WUkd7tIi7pyE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=BqQM+839jzhYlHAIrJv3O+EbQ8zY1nmEsOoo+Lg0AcTrOEaR0ASsRjspB7Zxo3jdvRQj4Tk/fqt+A5FrFLn++7MSpTYgfQuEfxJwFlHlgK520Ng5k1yVZiRmL5aHU6o1XVm8BsifYPTVwO/aeEOLggBrv/hzMzhYYWm903KGqQg= 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 4Wq6r16B6Gz4f3n69; Thu, 22 Aug 2024 10:40:17 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 0384C1A058E; Thu, 22 Aug 2024 10:40:33 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgCHr4UapcZmqbd1CQ--.38129S8; Thu, 22 Aug 2024 10:40:32 +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 Subject: [PATCH v2 04/25] ext4: avoid use-after-free in ext4_ext_show_leaf() Date: Thu, 22 Aug 2024 10:35:24 +0800 Message-Id: <20240822023545.1994557-5-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--.38129S8 X-Coremail-Antispam: 1UD129KBjvJXoWxWF4xAr48XryDJr4UAr47Jwb_yoW5Xw1kp3 sxur1DKr45JanFgrWDXa18Ar12ka1UG3y7GrW7Krya9FW5X3WFgF1xt3WFvFZ5XFW8Xas0 yr48tryUGa43Ca7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQY14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwAKzVCY07xG64k0F24lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l 4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67 AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8I cVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY6xAIw20EY4 v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AK xVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUbT7KDUUUUU== X-CM-SenderInfo: 5olet0hnxqqx5xdzvxpfor3voofrz/1tbiAgADBWbFpZhEEwAAsN Content-Type: text/plain; charset="utf-8" From: Baokun Li In ext4_find_extent(), path may be freed by error or be reallocated, so using a previously saved *ppath may have been freed and thus may trigger use-after-free, as follows: ext4_split_extent path =3D *ppath; ext4_split_extent_at(ppath) path =3D ext4_find_extent(ppath) ext4_split_extent_at(ppath) // ext4_find_extent fails to free path // but zeroout succeeds ext4_ext_show_leaf(inode, path) eh =3D path[depth].p_hdr // path use-after-free !!! Similar to ext4_split_extent_at(), we use *ppath directly as an input to ext4_ext_show_leaf(). Fix a spelling error by the way. Same problem in ext4_ext_handle_unwritten_extents(). Since 'path' is only used in ext4_ext_show_leaf(), remove 'path' and use *ppath directly. This issue is triggered only when EXT_DEBUG is defined and therefore does not affect functionality. Signed-off-by: Baokun Li Reviewed-by: Jan Kara Reviewed-by: Ojaswin Mujoo Tested-by: Ojaswin Mujoo --- fs/ext4/extents.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index ff4cfd8edeb7..0224cf0ef19e 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3327,7 +3327,7 @@ static int ext4_split_extent_at(handle_t *handle, } =20 /* - * ext4_split_extents() splits an extent and mark extent which is covered + * ext4_split_extent() splits an extent and mark extent which is covered * by @map as split_flags indicates * * It may result in splitting the extent into multiple extents (up to thre= e) @@ -3403,7 +3403,7 @@ static int ext4_split_extent(handle_t *handle, goto out; } =20 - ext4_ext_show_leaf(inode, path); + ext4_ext_show_leaf(inode, *ppath); out: return err ? err : allocated; } @@ -3868,14 +3868,13 @@ ext4_ext_handle_unwritten_extents(handle_t *handle,= struct inode *inode, struct ext4_ext_path **ppath, int flags, unsigned int allocated, ext4_fsblk_t newblock) { - struct ext4_ext_path __maybe_unused *path =3D *ppath; int ret =3D 0; int err =3D 0; =20 ext_debug(inode, "logical block %llu, max_blocks %u, flags 0x%x, allocate= d %u\n", (unsigned long long)map->m_lblk, map->m_len, flags, allocated); - ext4_ext_show_leaf(inode, path); + ext4_ext_show_leaf(inode, *ppath); =20 /* * When writing into unwritten space, we should not fail to @@ -3972,7 +3971,7 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, s= truct inode *inode, if (allocated > map->m_len) allocated =3D map->m_len; map->m_len =3D allocated; - ext4_ext_show_leaf(inode, path); + ext4_ext_show_leaf(inode, *ppath); out2: return err ? err : allocated; } --=20 2.39.2