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drm: Fix authentication kernel crash

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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@vmware.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Thomas Hellstrom
2012-01-24 18:54:21 +01:00
committed by Dave Airlie
parent 15b63d3526
commit 598781d711
3 changed files with 11 additions and 1 deletions
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1
include/drm/drmP.h
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@@ -1328,6 +1328,7 @@ 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);