linux-kernel - Re: [PATCH] ceph: kstrdup() memory handling

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Date:	Mon, 23 Mar 2015 12:03:42 +0800
From:	严正 <zyan@...hat.com>
To:	Sanidhya Kashyap <sanidhya.gatech@...il.com>
Cc:	sage@...hat.com, ceph-devel@...r.kernel.org,
	linux-kernel@...r.kernel.org, taesoo@...ech.edu,
	changwoo@...ech.edu, sanidhya@...ech.edu, blee@...ech.edu
Subject: Re: [PATCH] ceph: kstrdup() memory handling


> 在 2015年3月22日，00:54，Sanidhya Kashyap <sanidhya.gatech@...il.com> 写道：
> 
> Currently, there is no check for the kstrdup() for r_path2, r_path1 and snapdir_name
> as various locations as there is a possibility of failure during memory pressure.
> Therefore, returning ENOMEM where the checks have been missed.
> 
> Signed-off-by: Sanidhya Kashyap <sanidhya.gatech@...il.com>
> ---
> fs/ceph/dir.c   | 11 +++++++++++
> fs/ceph/super.c |  8 ++++++++
> fs/ceph/xattr.c |  7 +++++++
> 3 files changed, 26 insertions(+)
> 
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index 83e9976..be32703 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -344,6 +344,12 @@ more:
> 		req->r_direct_hash = ceph_frag_value(frag);
> 		req->r_direct_is_hash = true;
> 		req->r_path2 = kstrdup(fi->last_name, GFP_NOFS);
> +		if (!req->r_path2) {
> +			iput(inode);
> +			ceph_mdsc_put_request(req);
> +			return -ENOMEM;
> +		}
> +
> 		req->r_readdir_offset = fi->next_offset;
> 		req->r_args.readdir.frag = cpu_to_le32(frag);
> 		err = ceph_mdsc_do_request(mdsc, NULL, req);
> @@ -758,6 +764,11 @@ static int ceph_symlink(struct inode *dir, struct dentry *dentry,
> 	req->r_dentry = dget(dentry);
> 	req->r_num_caps = 2;
> 	req->r_path2 = kstrdup(dest, GFP_NOFS);
> +	if (!req->r_path2) {
> +		err = -ENOMEM;
> +		ceph_mdsc_put_request(req);
> +		goto out;
> +	}
> 	req->r_locked_dir = dir;
> 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
> 	req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
> diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> index a63997b..8e68f53 100644
> --- a/fs/ceph/super.c
> +++ b/fs/ceph/super.c
> @@ -345,6 +345,9 @@ static int parse_mount_options(struct ceph_mount_options **pfsopt,
> 	fsopt->rsize = CEPH_RSIZE_DEFAULT;
> 	fsopt->rasize = CEPH_RASIZE_DEFAULT;
> 	fsopt->snapdir_name = kstrdup(CEPH_SNAPDIRNAME_DEFAULT, GFP_KERNEL);
> +	if (!fsopt->snapdir_name)
> +		goto out;
> +
> 	fsopt->caps_wanted_delay_min = CEPH_CAPS_WANTED_DELAY_MIN_DEFAULT;
> 	fsopt->caps_wanted_delay_max = CEPH_CAPS_WANTED_DELAY_MAX_DEFAULT;
> 	fsopt->cap_release_safety = CEPH_CAP_RELEASE_SAFETY_DEFAULT;
> @@ -730,6 +733,11 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
> 	if (IS_ERR(req))
> 		return ERR_CAST(req);
> 	req->r_path1 = kstrdup(path, GFP_NOFS);
> +	if (!req->r_path1) {
> +		root = ERR_PTR(-ENOMEM);
> +		goto out;
> +	}
> +
> 	req->r_ino1.ino = CEPH_INO_ROOT;
> 	req->r_ino1.snap = CEPH_NOSNAP;
> 	req->r_started = started;
> diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
> index 5a492ca..299eb83 100644
> --- a/fs/ceph/xattr.c
> +++ b/fs/ceph/xattr.c
> @@ -883,6 +883,11 @@ static int ceph_sync_setxattr(struct dentry *dentry, const char *name,
> 	req->r_num_caps = 1;
> 	req->r_args.setxattr.flags = cpu_to_le32(flags);
> 	req->r_path2 = kstrdup(name, GFP_NOFS);
> +	if (!req->r_path2) {
> +		ceph_mdsc_put_request(req);
> +		err = -ENOMEM;
> +		goto out;
> +	}
> 
> 	req->r_pagelist = pagelist;
> 	pagelist = NULL;
> @@ -1024,6 +1029,8 @@ static int ceph_send_removexattr(struct dentry *dentry, const char *name)
> 	req->r_inode_drop = CEPH_CAP_XATTR_SHARED;
> 	req->r_num_caps = 1;
> 	req->r_path2 = kstrdup(name, GFP_NOFS);
> +	if (!req->r_path2)
> +		return -ENOMEM;
> 
> 	err = ceph_mdsc_do_request(mdsc, NULL, req);
> 	ceph_mdsc_put_request(req);
> -- 

Added to our testing branch (with some minor modifications. take inode/dentry references after kstrdup)

Thank
Yan, Zheng

> 2.1.0
> 

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