Message ID | 20210709200717.3676376-1-Julia.Lawall@inria.fr (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | drm/of: free the right object | expand |
On Fri, Jul 09, 2021 at 10:07:17PM +0200, Julia Lawall wrote: > There is no need to free a NULL value. Instead, free the object > that is leaking due to the iterator. > > The semantic patch that finds this problem is as follows: > > // <smpl> > @@ > expression x,e; > identifier f; > @@ > x = f(...); > if (x == NULL) { > ... when any > when != x = e > * of_node_put(x); > ... > } > // </smpl> > > Fixes: 6529007522de ("drm: of: Add drm_of_lvds_get_dual_link_pixel_order") > Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr> Applied to drm-misc-next, thanks for your patch. Random rant about this for_each_child_of_node(): - not documented with kerneldoc - very dangerous since the seemingly correct usage leaks What we've done here for similar refcounted iterators is a 3 step process: - iter_init() - for_each_iter() macro - iter_fini(), which has to be always called after iter_init and cleans up the last reference. Then it's a lot more obvious that you call iter_fini() when you break out of a loop. Trying to hide that in the for_each macro is a bit much. Cheers, Daniel > > --- > drivers/gpu/drm/drm_of.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c > index ca04c34e8251..197c57477344 100644 > --- a/drivers/gpu/drm/drm_of.c > +++ b/drivers/gpu/drm/drm_of.c > @@ -315,7 +315,7 @@ static int drm_of_lvds_get_remote_pixels_type( > > remote_port = of_graph_get_remote_port(endpoint); > if (!remote_port) { > - of_node_put(remote_port); > + of_node_put(endpoint); > return -EPIPE; > } > >
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c index ca04c34e8251..197c57477344 100644 --- a/drivers/gpu/drm/drm_of.c +++ b/drivers/gpu/drm/drm_of.c @@ -315,7 +315,7 @@ static int drm_of_lvds_get_remote_pixels_type( remote_port = of_graph_get_remote_port(endpoint); if (!remote_port) { - of_node_put(remote_port); + of_node_put(endpoint); return -EPIPE; }
There is no need to free a NULL value. Instead, free the object that is leaking due to the iterator. The semantic patch that finds this problem is as follows: // <smpl> @@ expression x,e; identifier f; @@ x = f(...); if (x == NULL) { ... when any when != x = e * of_node_put(x); ... } // </smpl> Fixes: 6529007522de ("drm: of: Add drm_of_lvds_get_dual_link_pixel_order") Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr> --- drivers/gpu/drm/drm_of.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)