From: Javier Martinez Canillas <javierm@redhat.com> To: linux-kernel@vger.kernel.org Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, Daniel Vetter <daniel.vetter@intel.com>, Javier Martinez Canillas <javierm@redhat.com>, Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter <daniel@ffwll.ch>, Helge Deller <deller@gmx.de>, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [PATCH v2 1/4] fbdev: Prevent possible use-after-free in fb_release() Date: Thu, 5 May 2022 13:31:24 +0200 [thread overview] Message-ID: <20220505113128.264963-2-javierm@redhat.com> (raw) In-Reply-To: <20220505113128.264963-1-javierm@redhat.com> From: Daniel Vetter <daniel.vetter@ffwll.ch> Most fbdev drivers have issues with the fb_info lifetime, because call to framebuffer_release() from their driver's .remove callback, rather than doing from fbops.fb_destroy callback. Doing that will destroy the fb_info too early, while references to it may still exist, leading to a use-after-free error. To prevent this, check the fb_info reference counter when attempting to kfree the data structure in framebuffer_release(). That will leak it but at least will prevent the mentioned error. Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> --- (no changes since v1) drivers/video/fbdev/core/fbsysfs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index 8c1ee9ecec3d..c2a60b187467 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -80,6 +80,10 @@ void framebuffer_release(struct fb_info *info) { if (!info) return; + + if (WARN_ON(refcount_read(&info->count))) + return; + kfree(info->apertures); kfree(info); } -- 2.35.1
WARNING: multiple messages have this Message-ID (diff)
From: Javier Martinez Canillas <javierm@redhat.com> To: linux-kernel@vger.kernel.org Cc: linux-fbdev@vger.kernel.org, Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter <daniel.vetter@ffwll.ch>, Helge Deller <deller@gmx.de>, Javier Martinez Canillas <javierm@redhat.com>, dri-devel@lists.freedesktop.org, Daniel Vetter <daniel.vetter@intel.com> Subject: [PATCH v2 1/4] fbdev: Prevent possible use-after-free in fb_release() Date: Thu, 5 May 2022 13:31:24 +0200 [thread overview] Message-ID: <20220505113128.264963-2-javierm@redhat.com> (raw) In-Reply-To: <20220505113128.264963-1-javierm@redhat.com> From: Daniel Vetter <daniel.vetter@ffwll.ch> Most fbdev drivers have issues with the fb_info lifetime, because call to framebuffer_release() from their driver's .remove callback, rather than doing from fbops.fb_destroy callback. Doing that will destroy the fb_info too early, while references to it may still exist, leading to a use-after-free error. To prevent this, check the fb_info reference counter when attempting to kfree the data structure in framebuffer_release(). That will leak it but at least will prevent the mentioned error. Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> --- (no changes since v1) drivers/video/fbdev/core/fbsysfs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index 8c1ee9ecec3d..c2a60b187467 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -80,6 +80,10 @@ void framebuffer_release(struct fb_info *info) { if (!info) return; + + if (WARN_ON(refcount_read(&info->count))) + return; + kfree(info->apertures); kfree(info); } -- 2.35.1
next prev parent reply other threads:[~2022-05-05 11:32 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-05 11:31 [PATCH v2 0/4] fbdev: Fix use-after-free caused by wrong fb_info cleanup in drivers Javier Martinez Canillas 2022-05-05 11:31 ` Javier Martinez Canillas 2022-05-05 11:31 ` Javier Martinez Canillas [this message] 2022-05-05 11:31 ` [PATCH v2 1/4] fbdev: Prevent possible use-after-free in fb_release() Javier Martinez Canillas 2022-05-05 11:31 ` [PATCH v2 2/4] fbdev: simplefb: Cleanup fb_info in .fb_destroy rather than .remove Javier Martinez Canillas 2022-05-05 11:31 ` Javier Martinez Canillas 2022-05-05 11:31 ` [PATCH v2 3/4] fbdev: efifb: " Javier Martinez Canillas 2022-05-05 11:31 ` Javier Martinez Canillas 2022-05-05 11:31 ` [PATCH v2 4/4] fbdev: vesafb: " Javier Martinez Canillas 2022-05-05 11:31 ` Javier Martinez Canillas 2022-05-05 11:51 ` Thomas Zimmermann 2022-05-05 11:51 ` Thomas Zimmermann 2022-05-05 13:02 ` Daniel Vetter 2022-05-05 13:02 ` Daniel Vetter 2022-05-05 13:19 ` Javier Martinez Canillas
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