From: Zizhi Wo wozizhi@huawei.com
hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IB5UKT
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Commit 27756c07db81 ("cachefiles: add consistency check for copen/cread") added some validation to prevent malicious commands. But there is another case: if copen is maliciously called in the user mode, it may delete the request corresponding to the random id. And the request may have not been read yet.
Note that when the object is set to reopen, the open request will be done with the still reopen state in above case. As a result, the request corresponding to this object is always skipped in select_req function, so the read request is never completed and blocks other process.
Fix this issue by simply set object to close if its id < 0 in copen. In addition, the "ret != 0" condition is no need in get_fd function as it always meet, remove it.
Signed-off-by: Zizhi Wo wozizhi@huawei.com Signed-off-by: Baokun Li libaokun1@huawei.com --- fs/cachefiles/ondemand.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c index 9f3e7d994aed..528da20e1119 100644 --- a/fs/cachefiles/ondemand.c +++ b/fs/cachefiles/ondemand.c @@ -189,6 +189,7 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) radix_tree_delete(&cache->reqs, id); xa_unlock(&cache->reqs);
+ info = req->object->private; /* fail OPEN request if copen format is invalid */ ret = kstrtol(psize, 0, &size); if (ret) { @@ -208,7 +209,6 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) goto out; }
- info = req->object->private; spin_lock(&info->lock); /* The anonymous fd was closed before copen. */ if (info->ondemand_id == CACHEFILES_ONDEMAND_ID_CLOSED) { @@ -228,6 +228,11 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) wake_up_all(&cache->daemon_pollwq);
out: + spin_lock(&info->lock); + /* Need to set object close to avoid reopen status continuing */ + if (info->ondemand_id == CACHEFILES_ONDEMAND_ID_CLOSED) + cachefiles_ondemand_set_object_close(req->object); + spin_unlock(&info->lock); complete(&req->done); return ret; } @@ -323,7 +328,7 @@ static int cachefiles_ondemand_get_fd(struct cachefiles_req *req, err: spin_lock(&req->object->private->lock); /* Avoid marking an opened object as closed. */ - if (ret && object->private->ondemand_id <= 0) + if (object->private->ondemand_id <= 0) cachefiles_ondemand_set_object_close(req->object); spin_unlock(&req->object->private->lock);