[PATCH 03/14] GPU-DRM-OMAP: Less function calls in tiler_map_show() after error detection

SF Markus Elfring
2016-09-21T16:40:59Z

Date: Wed, 21 Sep 2016 13:16:20 +0200

The kfree() function was called in up to two cases
by the tiler_map_show() function during error handling even if
the passed variable contained a null pointer.

* Adjust jump targets according to the Linux coding style convention.

* Split a condition check for memory allocation failures so that
each pointer from these function calls will be checked immediately.

See also background information:
Topic "CWE-754: Improper check for unusual or exceptional conditions"
Link: https://cwe.mitre.org/data/definitions/754.html

* Return directly after a call of the function "kmalloc_array" failed
at the beginning.

* Move an assignment for the local variable "w_adj" behind the first
memory allocation.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c
index 3a4f91b..60beeb9 100644
--- a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c
+++ b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c
@@ -916,11 +916,14 @@ int tiler_map_show(struct seq_file *s, void *arg)
}

h_adj = omap_dmm->container_height / ydiv;
- w_adj = omap_dmm->container_width / xdiv;
map = kmalloc_array(h_adj, sizeof(*map), GFP_KERNEL);
+ if (!map)
+ return 0;
+
+ w_adj = omap_dmm->container_width / xdiv;
global_map = kmalloc_array(h_adj, w_adj + 1, GFP_KERNEL);
- if (!map || !global_map)
- goto error;
+ if (!global_map)
+ goto free_map;

for (lut_idx = 0; lut_idx < omap_dmm->num_lut; lut_idx++) {
memset(map, 0, h_adj * sizeof(*map));
@@ -982,10 +985,9 @@ int tiler_map_show(struct seq_file *s, void *arg)
}
}

-error:
- kfree(map);
kfree(global_map);
-
+ free_map:
+ kfree(map);
return 0;
}
#endif
--
2.10.0