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Date: Fri, 3 Feb 2012 19:28:53 +0100
From: Stefan Bader <stefan.bader@...onical.com>
To: Thomas Hellstrom <thellstrom@...are.com>
Cc: Dave Airlie <airlied@...hat.com>,
Stefan Bader <stefan.bader@...onical.com>,
linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [2.6.32+drm33-longterm] Patch "drm: Fix authentication kernel crash" has been added to staging queue
This is a note to let you know that I have just added a patch titled
drm: Fix authentication kernel crash
to the drm-next branch of the 2.6.32+drm33-longterm tree which can be found at
http://git.kernel.org/?p=linux/kernel/git/smb/linux-2.6.32.y-drm33.z.git;a=shortlog;h=refs/heads/drm-next
or
http://kernel.ubuntu.com/git?p=smb/linux-2.6.32.y-drm33.z.git;a=shortlog;h=refs/heads/drm-next
If you, or anyone else, feels it should not be added to the drm33-longterm tree,
please reply to this email not later than 8 days after this email was sent.
Thanks.
-Stefan
------
>From 26487be3d861e50dcfd4b19199e3c206d3700678 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thellstrom@...are.com>
Date: Tue, 24 Jan 2012 18:54:21 +0100
Subject: [PATCH] drm: Fix authentication kernel crash
commit 598781d71119827b454fd75d46f84755bca6f0c6 upstream.
If the master tries to authenticate a client using drm_authmagic and
that client has already closed its drm file descriptor,
either wilfully or because it was terminated, the
call to drm_authmagic will dereference a stale pointer into kmalloc'ed memory
and corrupt it.
Typically this results in a hard system hang.
This patch fixes that problem by removing any authentication tokens
(struct drm_magic_entry) open for a file descriptor when that file
descriptor is closed.
Signed-off-by: Thomas Hellstrom <thellstrom@...are.com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
Signed-off-by: Dave Airlie <airlied@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@...onical.com>
---
drivers/gpu/drm/drm_auth.c | 6 +++++-
drivers/gpu/drm/drm_fops.c | 5 +++++
include/drm/drmP.h | 1 +
3 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 932b5aa..d676d49 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -102,7 +102,7 @@ static int drm_add_magic(struct drm_master *master, struct drm_file *priv,
* Searches and unlinks the entry in drm_device::magiclist with the magic
* number hash key, while holding the drm_device::struct_mutex lock.
*/
-static int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
+int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
{
struct drm_magic_entry *pt;
struct drm_hash_item *hash;
@@ -137,6 +137,8 @@ static int drm_remove_magic(struct drm_master *master, drm_magic_t magic)
* If there is a magic number in drm_file::magic then use it, otherwise
* searches an unique non-zero magic number and add it associating it with \p
* file_priv.
+ * This ioctl needs protection by the drm_global_mutex, which protects
+ * struct drm_file::magic and struct drm_magic_entry::priv.
*/
int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
@@ -174,6 +176,8 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
* \return zero if authentication successed, or a negative number otherwise.
*
* Checks if \p file_priv is associated with the magic number passed in \arg.
+ * This ioctl needs protection by the drm_global_mutex, which protects
+ * struct drm_file::magic and struct drm_magic_entry::priv.
*/
int drm_authmagic(struct drm_device *dev, void *data,
struct drm_file *file_priv)
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index ba14553..519161e 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -449,6 +449,11 @@ int drm_release(struct inode *inode, struct file *filp)
(long)old_encode_dev(file_priv->minor->device),
dev->open_count);
+ /* Release any auth tokens that might point to this file_priv,
+ (do that under the drm_global_mutex) */
+ if (file_priv->magic)
+ (void) drm_remove_magic(file_priv->master, file_priv->magic);
+
/* if the master has gone away we can't do anything with the lock */
if (file_priv->minor->master)
drm_master_release(dev, filp);
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 66713c6..ebab6a6 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1221,6 +1221,7 @@ extern int drm_getmagic(struct drm_device *dev, void *data,
struct drm_file *file_priv);
extern int drm_authmagic(struct drm_device *dev, void *data,
struct drm_file *file_priv);
+extern int drm_remove_magic(struct drm_master *master, drm_magic_t magic);
/* Cache management (drm_cache.c) */
void drm_clflush_pages(struct page *pages[], unsigned long num_pages);
--
1.7.5.4
--
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