From 74eadb6f62282d6572e05b851b45ce69d911ff36 Mon Sep 17 00:00:00 2001
From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Date: Wed, 9 Feb 2022 07:03:11 +0100
Subject: drm/nouveau: Fix a potential theorical leak in
 nouveau_get_backlight_name()
Git-commit: ab244be47a8f111bc82496a8a20c907236e37f95
Patch-mainline: v5.18-rc7
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

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
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/nouveau/nouveau_backlight.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index daf9f87477ba..a2141d3d9b1d 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -46,8 +46,9 @@ 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);
@@ -414,7 +415,7 @@ 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;
 	}
@@ -442,7 +443,7 @@ 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;
-- 
2.38.1