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v9fs: fix error handling in v9fs_session_init()
On failure, v9fs_session_init() returns with the v9fs_session_info
struct partially initialized and expects the caller to invoke
v9fs_session_close() to clean it up; however, it doesn't track whether
the bdi is initialized or not and curiously invokes bdi_destroy() in
both vfs_session_init() failure path too.
A. If v9fs_session_init() fails before the bdi is initialized, the
follow-up v9fs_session_close() will invoke bdi_destroy() on an
uninitialized bdi.
B. If v9fs_session_init() fails after the bdi is initialized,
bdi_destroy() will be called twice on the same bdi - once in the
failure path of v9fs_session_init() and then by
v9fs_session_close().
A is broken no matter what. B used to be okay because bdi_destroy()
allowed being invoked multiple times on the same bdi, which BTW was
broken in its own way - if bdi_destroy() was invoked on an initialiezd
but !registered bdi, it'd fail to free percpu counters. Since
f0054bb1e1
("writeback: move backing_dev_info->wb_lock and
->worklist into bdi_writeback"), this no longer work - bdi_destroy()
on an initialized but not registered bdi works correctly but multiple
invocations of bdi_destroy() is no longer allowed.
The obvious culprit here is v9fs_session_init()'s odd and broken error
behavior. It should simply clean up after itself on failures. This
patch makes the following updates to v9fs_session_init().
* @rc -> @retval error return propagation removed. It didn't serve
any purpose. Just use @rc.
* Move addition to v9fs_sessionlist to the end of the function so that
incomplete sessions are not put on the list or iterated and error
path doesn't have to worry about it.
* Update error handling so that it cleans up after itself.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
parent
5857cd637b
commit
412a19b64a
50
fs/9p/v9fs.c
50
fs/9p/v9fs.c
@ -320,31 +320,21 @@ fail_option_alloc:
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struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
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const char *dev_name, char *data)
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{
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int retval = -EINVAL;
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struct p9_fid *fid;
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int rc;
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int rc = -ENOMEM;
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v9ses->uname = kstrdup(V9FS_DEFUSER, GFP_KERNEL);
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if (!v9ses->uname)
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return ERR_PTR(-ENOMEM);
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goto err_names;
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v9ses->aname = kstrdup(V9FS_DEFANAME, GFP_KERNEL);
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if (!v9ses->aname) {
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kfree(v9ses->uname);
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return ERR_PTR(-ENOMEM);
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}
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if (!v9ses->aname)
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goto err_names;
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init_rwsem(&v9ses->rename_sem);
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rc = bdi_setup_and_register(&v9ses->bdi, "9p");
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if (rc) {
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kfree(v9ses->aname);
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kfree(v9ses->uname);
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return ERR_PTR(rc);
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}
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spin_lock(&v9fs_sessionlist_lock);
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list_add(&v9ses->slist, &v9fs_sessionlist);
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spin_unlock(&v9fs_sessionlist_lock);
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if (rc)
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goto err_names;
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v9ses->uid = INVALID_UID;
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v9ses->dfltuid = V9FS_DEFUID;
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@ -352,10 +342,9 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
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v9ses->clnt = p9_client_create(dev_name, data);
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if (IS_ERR(v9ses->clnt)) {
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retval = PTR_ERR(v9ses->clnt);
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v9ses->clnt = NULL;
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rc = PTR_ERR(v9ses->clnt);
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p9_debug(P9_DEBUG_ERROR, "problem initializing 9p client\n");
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goto error;
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goto err_bdi;
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}
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v9ses->flags = V9FS_ACCESS_USER;
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@ -368,10 +357,8 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
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}
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rc = v9fs_parse_options(v9ses, data);
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if (rc < 0) {
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retval = rc;
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goto error;
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}
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if (rc < 0)
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goto err_clnt;
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v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;
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@ -405,10 +392,9 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
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fid = p9_client_attach(v9ses->clnt, NULL, v9ses->uname, INVALID_UID,
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v9ses->aname);
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if (IS_ERR(fid)) {
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retval = PTR_ERR(fid);
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fid = NULL;
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rc = PTR_ERR(fid);
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p9_debug(P9_DEBUG_ERROR, "cannot attach\n");
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goto error;
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goto err_clnt;
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}
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if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
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@ -420,12 +406,20 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
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/* register the session for caching */
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v9fs_cache_session_get_cookie(v9ses);
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#endif
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spin_lock(&v9fs_sessionlist_lock);
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list_add(&v9ses->slist, &v9fs_sessionlist);
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spin_unlock(&v9fs_sessionlist_lock);
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return fid;
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error:
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err_clnt:
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p9_client_destroy(v9ses->clnt);
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err_bdi:
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bdi_destroy(&v9ses->bdi);
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return ERR_PTR(retval);
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err_names:
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kfree(v9ses->uname);
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kfree(v9ses->aname);
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return ERR_PTR(rc);
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}
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/**
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@ -130,11 +130,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
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fid = v9fs_session_init(v9ses, dev_name, data);
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if (IS_ERR(fid)) {
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retval = PTR_ERR(fid);
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/*
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* we need to call session_close to tear down some
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* of the data structure setup by session_init
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*/
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goto close_session;
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goto free_session;
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}
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sb = sget(fs_type, NULL, v9fs_set_super, flags, v9ses);
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@ -195,8 +191,8 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
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clunk_fid:
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p9_client_clunk(fid);
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close_session:
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v9fs_session_close(v9ses);
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free_session:
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kfree(v9ses);
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return ERR_PTR(retval);
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