From ed15511a773df86205bda66c37193569575ae828 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= <jose.exposito89@gmail.com>
Date: Wed, 12 Feb 2025 09:49:12 +0100
Subject: [PATCH] drm/vkms: Fix use after free and double free on init error
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If the driver initialization fails, the vkms_exit() function might
access an uninitialized or freed default_config pointer and it might
double free it.
Fix both possible errors by initializing default_config only when the
driver initialization succeeded.
Reported-by: Louis Chauvet <louis.chauvet@bootlin.com>
Closes: https://lore.kernel.org/all/Z5uDHcCmAwiTsGte@louis-chauvet-laptop/
Fixes: 2df7af93fdad ("drm/vkms: Add vkms_config type")
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Reviewed-by: Thomas Zimmermann <tzimmremann@suse.de>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250212084912.3196-1-jose.exposito89@gmail.com
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
drivers/gpu/drm/vkms/vkms_drv.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 7c142bfc3bd9d..b6de91134a225 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -235,17 +235,19 @@ static int __init vkms_init(void)
if (!config)
return -ENOMEM;
- default_config = config;
-
config->cursor = enable_cursor;
config->writeback = enable_writeback;
config->overlay = enable_overlay;
ret = vkms_create(config);
- if (ret)
+ if (ret) {
kfree(config);
+ return ret;
+ }
- return ret;
+ default_config = config;
+
+ return 0;
}
static void vkms_destroy(struct vkms_config *config)
@@ -269,9 +271,10 @@ static void vkms_destroy(struct vkms_config *config)
static void __exit vkms_exit(void)
{
- if (default_config->dev)
- vkms_destroy(default_config);
+ if (!default_config)
+ return;
+ vkms_destroy(default_config);
kfree(default_config);
}
--
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