From nobody Wed Dec 17 15:19:18 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 AD72E101C8; 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=1724294438; cv=none; b=DvCMYDAr8xH+6mb7m9eQSuD08GILUtTuBmxtmWLjA9pDUndr4cEjFChF/pNWdWrH/NZLS8c57o4Dz//px3X679yR4uUTwlbjM88xfDFv2tzdtdhrmp3fiui1H+2REwAg5/gVjBApCgt6tSrav/whgeQyCXJpdKo0FR0btXkTZG8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724294438; c=relaxed/simple; bh=pKPYfU+9cPa8S/XXTaMvpyANFQq6lHh45jNbRny3RJA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Jq9bhP2h/CqkJ5kdExJ4sre4udXF0P6rSllSE0fFto0nTaTdAEI5IjYIguGUAWhYpiAThMfYSu9qT6ZGmsk99iYsUirjom8o9Nvoe8QVC84+8RsH9/sPQIGxdZsejRTsDyEHtH30aD1EQIrLgZINpFCvZS3o9ySdK493vMBtHGk= 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 [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Wq6r764gyz4f3jt1; Thu, 22 Aug 2024 10:40:23 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 86E7A1A018D; 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--.38129S9; 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 05/25] ext4: update orig_path in ext4_find_extent() Date: Thu, 22 Aug 2024 10:35:25 +0800 Message-Id: <20240822023545.1994557-6-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--.38129S9 X-Coremail-Antispam: 1UD129KBjvJXoWxWF47GF1rXr17urW3Zw4Dtwb_yoW5GrW7pr nxCryxKr18X3yUKw4xK3WDZryUKa1jka1UJrWftr1jvFyjq348XF1xt3WYqFyYgrW8ZFya yr18tw1UWa45J3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 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/1tbiAgADBWbFpZhEFAAAsK Content-Type: text/plain; charset="utf-8" From: Baokun Li In ext4_find_extent(), if the path is not big enough, we free it and set *orig_path to NULL. But after reallocating and successfully initializing the path, we don't update *orig_path, in which case the caller gets a valid path but a NULL ppath, and this may cause a NULL pointer dereference or a path memory leak. For example: ext4_split_extent path =3D *ppath =3D 2000 ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path =3D 2000); *orig_path =3D path =3D NULL; path =3D kcalloc() =3D 3000 ext4_split_extent_at(*ppath =3D NULL) path =3D *ppath; ex =3D path[depth].p_ext; // NULL pointer dereference! =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: kernel NULL pointer dereference, address: 0000000000000010 CPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847 RIP: 0010:ext4_split_extent_at+0x6d/0x560 Call Trace: ext4_split_extent.isra.0+0xcb/0x1b0 ext4_ext_convert_to_initialized+0x168/0x6c0 ext4_ext_handle_unwritten_extents+0x325/0x4d0 ext4_ext_map_blocks+0x520/0xdb0 ext4_map_blocks+0x2b0/0x690 ext4_iomap_begin+0x20e/0x2c0 [...] =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 Therefore, *orig_path is updated when the extent lookup succeeds, so that the caller can safely use path or *ppath. 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 | 3 ++- fs/ext4/move_extent.c | 1 - 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 0224cf0ef19e..5879aef159d8 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -957,6 +957,8 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block, =20 ext4_ext_show_path(inode, path); =20 + if (orig_path) + *orig_path =3D path; return path; =20 err: @@ -3268,7 +3270,6 @@ static int ext4_split_extent_at(handle_t *handle, } depth =3D ext_depth(inode); ex =3D path[depth].p_ext; - *ppath =3D path; =20 if (EXT4_EXT_MAY_ZEROOUT & split_flag) { if (split_flag & (EXT4_EXT_DATA_VALID1|EXT4_EXT_DATA_VALID2)) { diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c index 204f53b23622..c95e3e526390 100644 --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -36,7 +36,6 @@ get_ext_path(struct inode *inode, ext4_lblk_t lblock, *ppath =3D NULL; return -ENODATA; } - *ppath =3D path; return 0; } =20 --=20 2.39.2