From 5a67657a2e90c9e4a48518f95d4ba7777aa20fbb Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sun, 12 Sep 2010 19:55:25 -0400 Subject: SUNRPC: Fix race corrupting rpc upcall If rpc_queue_upcall() adds a new upcall to the rpci->pipe list just after rpc_pipe_release calls rpc_purge_list(), but before it calls gss_pipe_release (as rpci->ops->release_pipe(inode)), then the latter will free a message without deleting it from the rpci->pipe list. We will be left with a freed object on the rpc->pipe list. Most frequent symptoms are kernel crashes in rpc.gssd system calls on the pipe in question. Reported-by: J. Bruce Fields Signed-off-by: Trond Myklebust Cc: stable@kernel.org --- net/sunrpc/rpc_pipe.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/sunrpc/rpc_pipe.c') diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index 95ccbcf45d3e..41a762f82630 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -48,7 +48,7 @@ static void rpc_purge_list(struct rpc_inode *rpci, struct list_head *head, return; do { msg = list_entry(head->next, struct rpc_pipe_msg, list); - list_del(&msg->list); + list_del_init(&msg->list); msg->errno = err; destroy_msg(msg); } while (!list_empty(head)); @@ -208,7 +208,7 @@ rpc_pipe_release(struct inode *inode, struct file *filp) if (msg != NULL) { spin_lock(&inode->i_lock); msg->errno = -EAGAIN; - list_del(&msg->list); + list_del_init(&msg->list); spin_unlock(&inode->i_lock); rpci->ops->destroy_msg(msg); } @@ -268,7 +268,7 @@ rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset) if (res < 0 || msg->len == msg->copied) { filp->private_data = NULL; spin_lock(&inode->i_lock); - list_del(&msg->list); + list_del_init(&msg->list); spin_unlock(&inode->i_lock); rpci->ops->destroy_msg(msg); } -- cgit v1.2.2 From 006abe887c5e637d059c44310de6c92f36aded3b Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sun, 12 Sep 2010 19:55:25 -0400 Subject: SUNRPC: Fix a race in rpc_info_open There is a race between rpc_info_open and rpc_release_client() in that nothing stops a process from opening the file after the clnt->cl_kref goes to zero. Fix this by using atomic_inc_unless_zero()... Reported-by: J. Bruce Fields Signed-off-by: Trond Myklebust Cc: stable@kernel.org --- net/sunrpc/rpc_pipe.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'net/sunrpc/rpc_pipe.c') diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index 41a762f82630..8c8eef2b8f26 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -371,21 +371,23 @@ rpc_show_info(struct seq_file *m, void *v) static int rpc_info_open(struct inode *inode, struct file *file) { - struct rpc_clnt *clnt; + struct rpc_clnt *clnt = NULL; int ret = single_open(file, rpc_show_info, NULL); if (!ret) { struct seq_file *m = file->private_data; - mutex_lock(&inode->i_mutex); - clnt = RPC_I(inode)->private; - if (clnt) { - kref_get(&clnt->cl_kref); + + spin_lock(&file->f_path.dentry->d_lock); + if (!d_unhashed(file->f_path.dentry)) + clnt = RPC_I(inode)->private; + if (clnt != NULL && atomic_inc_not_zero(&clnt->cl_count)) { + spin_unlock(&file->f_path.dentry->d_lock); m->private = clnt; } else { + spin_unlock(&file->f_path.dentry->d_lock); single_release(inode, file); ret = -EINVAL; } - mutex_unlock(&inode->i_mutex); } return ret; } -- cgit v1.2.2