ring-buffer: Fix NULL pointer if rb_set_head_page() fails
authorSteven Rostedt <srostedt@redhat.com>
Fri, 30 Nov 2012 03:27:22 +0000 (22:27 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 17 Dec 2012 19:07:23 +0000 (11:07 -0800)
commit7c3432b14e30e1aebb7a19ea52a05928b383b272
tree6d2e2a92a95865defda0c84fe9347a15b494b9b8
parent5bab98768136ee54b82ef6dd7fc0ec1c41ef8431
ring-buffer: Fix NULL pointer if rb_set_head_page() fails

commit 54f7be5b831254199522523ccab4c3d954bbf576 upstream.

The function rb_set_head_page() searches the list of ring buffer
pages for a the page that has the HEAD page flag set. If it does
not find it, it will do a WARN_ON(), disable the ring buffer and
return NULL, as this should never happen.

But if this bug happens to happen, not all callers of this function
can handle a NULL pointer being returned from it. That needs to be
fixed.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/trace/ring_buffer.c