[PATCH 3/6] uprobes/tracing: Ensure inode != NULL in create_trace_uprobe()

[Oleg Nesterov <oleg@redhat.com>]

probe_event_enable/disable() check tu->inode != NULL at the start.
This is ugly, if igrab() can fail create_trace_uprobe() should not
succeed and "postpone" the failure.

Note: alloc_uprobe() should probably check igrab() != NULL as well.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 kernel/trace/trace_uprobe.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 7b75949..f02bbec 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -255,6 +255,8 @@ static int create_trace_uprobe(int argc, char **argv)
 
 	inode = igrab(path.dentry->d_inode);
 	path_put(&path);
+	if (!inode)
+		goto fail_address_parse;
 
 	ret = kstrtoul(arg, 0, &offset);
 	if (ret)
@@ -539,7 +541,7 @@ static int probe_event_enable(struct trace_uprobe *tu, int flag)
 	struct uprobe_trace_consumer *utc;
 	int ret = 0;
 
-	if (!tu->inode || tu->consumer)
+	if (tu->consumer)
 		return -EINTR;
 
 	utc = kzalloc(sizeof(struct uprobe_trace_consumer), GFP_KERNEL);
@@ -563,7 +565,7 @@ static int probe_event_enable(struct trace_uprobe *tu, int flag)
 
 static void probe_event_disable(struct trace_uprobe *tu, int flag)
 {
-	if (!tu->inode || !tu->consumer)
+	if (!tu->consumer)
 		return;
 
 	uprobe_unregister(tu->inode, tu->offset, &tu->consumer->cons);
-- 
1.5.5.1