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[5.4,06/43] drm/nouveau: Fix a potential theorical leak in nouveau_get_backlight_name()

Message ID 20220516193614.906147386@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

gregkh@linuxfoundation.org May 16, 2022, 7:36 p.m. UTC 
From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

[ Upstream commit ab244be47a8f111bc82496a8a20c907236e37f95 ]

If successful ida_simple_get() calls are not undone when needed, some
additional memory may be allocated and wasted.

Here, an ID between 0 and MAX_INT is required. If this ID is >=100, it is
not taken into account and is wasted. It should be released.

Instead of calling ida_simple_remove(), take advantage of the 'max'
parameter to require the ID not to be too big. Should it be too big, it
is not allocated and don't need to be freed.

While at it, use ida_alloc_xxx()/ida_free() instead to
ida_simple_get()/ida_simple_remove().
The latter is deprecated and more verbose.

Fixes: db1a0ae21461 ("drm/nouveau/bl: Assign different names to interfaces")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Lyude Paul <lyude@redhat.com>
[Fixed formatting warning from checkpatch]
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/9ba85bca59df6813dc029e743a836451d5173221.1644386541.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/nouveau/nouveau_backlight.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index c7a94c94dbf3..f2f3280c3a50 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -51,8 +51,9 @@  static bool
 nouveau_get_backlight_name(char backlight_name[BL_NAME_SIZE],
 			   struct nouveau_backlight *bl)
 {
-	const int nb = ida_simple_get(&bl_ida, 0, 0, GFP_KERNEL);
-	if (nb < 0 || nb >= 100)
+	const int nb = ida_alloc_max(&bl_ida, 99, GFP_KERNEL);
+
+	if (nb < 0)
 		return false;
 	if (nb > 0)
 		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
@@ -280,7 +281,7 @@  nouveau_backlight_init(struct drm_connector *connector)
 					    nv_encoder, ops, &props);
 	if (IS_ERR(bl->dev)) {
 		if (bl->id >= 0)
-			ida_simple_remove(&bl_ida, bl->id);
+			ida_free(&bl_ida, bl->id);
 		ret = PTR_ERR(bl->dev);
 		goto fail_alloc;
 	}
@@ -306,7 +307,7 @@  nouveau_backlight_fini(struct drm_connector *connector)
 		return;
 
 	if (bl->id >= 0)
-		ida_simple_remove(&bl_ida, bl->id);
+		ida_free(&bl_ida, bl->id);
 
 	backlight_device_unregister(bl->dev);
 	nv_conn->backlight = NULL;