NFS: Fix a tracepoint NULL-pointer dereference

Running xfstest generic/013 with the tracepoint nfs:nfs4_open_file
enabled produces a NULL-pointer dereference when calculating fileid and
filehandle of the opened file.  Fix this by checking if state is NULL
before trying to use the inode pointer.

Reported-by: Olga Kornievskaia <aglo@umich.edu>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/nfs4trace.h b/fs/nfs/nfs4trace.h
index 28df12e..671cf68 100644 (file)
--- a/fs/nfs/nfs4trace.h
+++ b/fs/nfs/nfs4trace.h
@@ -409,7 +409,7 @@ DECLARE_EVENT_CLASS(nfs4_open_event,
                        __entry->flags = flags;
                        __entry->fmode = (__force unsigned int)ctx->mode;
                        __entry->dev = ctx->dentry->d_sb->s_dev;
-                       if (!IS_ERR(state))
+                       if (!IS_ERR_OR_NULL(state))
                                inode = state->inode;
                        if (inode != NULL) {
                                __entry->fileid = NFS_FILEID(inode);