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authorIlija Hadzic <ihadzic@research.bell-labs.com>2013-04-02 17:56:10 +0400
committerDave Airlie <airlied@redhat.com>2013-04-03 00:44:38 +0400
commita8ec3a662921220fc058ed6f7f3674697876d218 (patch)
treee7c35670e35d4e5ace87b01c83652dfee006fdc4
parent7cebefe6cca5e8ff6ec9ba13ff9edb03d3c19fc7 (diff)
downloadlinux-a8ec3a662921220fc058ed6f7f3674697876d218.tar.xz
drm: correctly restore mappings if drm_open fails
If first drm_open fails, the error-handling path will incorrectly restore inode's mapping to NULL. This can cause the crash later on. Fix by separately storing away mapping pointers that drm_open can touch and restore each from its own respective variable if the call fails. Fixes: https://bugzilla.novell.com/show_bug.cgi?id=807850 (thanks to Michal Hocko for investigating investigating and finding the root cause of the bug) Reference: http://lists.freedesktop.org/archives/dri-devel/2013-March/036564.html v2: Use one variable to store file and inode mapping since they are the same at the function entry. Fix spelling mistakes in commit message. v3: Add reference to the original bug report. Reported-by: Marco Munderloh <munderl@tnt.uni-hannover.de> Tested-by: Marco Munderloh <munderl@tnt.uni-hannover.de> Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
-rw-r--r--drivers/gpu/drm/drm_fops.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 13fdcd10a605..429e07d0b0f1 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -123,6 +123,7 @@ int drm_open(struct inode *inode, struct file *filp)
int retcode = 0;
int need_setup = 0;
struct address_space *old_mapping;
+ struct address_space *old_imapping;
minor = idr_find(&drm_minors_idr, minor_id);
if (!minor)
@@ -137,6 +138,7 @@ int drm_open(struct inode *inode, struct file *filp)
if (!dev->open_count++)
need_setup = 1;
mutex_lock(&dev->struct_mutex);
+ old_imapping = inode->i_mapping;
old_mapping = dev->dev_mapping;
if (old_mapping == NULL)
dev->dev_mapping = &inode->i_data;
@@ -159,8 +161,8 @@ int drm_open(struct inode *inode, struct file *filp)
err_undo:
mutex_lock(&dev->struct_mutex);
- filp->f_mapping = old_mapping;
- inode->i_mapping = old_mapping;
+ filp->f_mapping = old_imapping;
+ inode->i_mapping = old_imapping;
iput(container_of(dev->dev_mapping, struct inode, i_data));
dev->dev_mapping = old_mapping;
mutex_unlock(&dev->struct_mutex);