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authorVegard Nossum <vegard.nossum@gmail.com>2008-12-02 13:38:47 +1000
committerDave Airlie <airlied@linux.ie>2008-12-29 17:47:22 +1000
commit1147c9cdd0f60f09a98702a9f865176af18a989f (patch)
tree4f3c33102566475cd145cf0235c1738d07b8b715 /include
parent7c1c2871a6a3a114853ec6836e9035ac1c0c7f7a (diff)
drm: fix leak of uninitialized data to userspace
...so drm_getunique() is trying to copy some uninitialized data to userspace. The ECX register contains the number of words that are left to copy -- so there are 5 * 4 = 20 bytes left. The offset of the first uninitialized byte (counting from the start of the string) is also 20 (i.e. 0xf65d2294&((1 << 5)-1) == 20). So somebody tried to copy 40 bytes when the string was only 19 long. In drm_set_busid() we have this code: dev->unique_len = 40; dev->unique = drm_alloc(dev->unique_len + 1, DRM_MEM_DRIVER); ... len = snprintf(dev->unique, dev->unique_len, pci:%04x:%02x:%02x.%d", ...so it seems that dev->unique is never updated to reflect the actual length of the string. The remaining bytes (20 in this case) are random uninitialized bytes that are copied into userspace. This patch fixes the problem by setting dev->unique_len after the snprintf(). airlied- I've had to fix this up to store the alloced size so we have it for drm_free later. Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com> Signed-off-by: Vegard Nossum <vegardno@thuin.ifi.uio.no> Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/drm/drmP.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 4c6e8298b424..c9cc618dbcfc 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -627,6 +627,7 @@ struct drm_master {
char *unique; /**< Unique identifier: e.g., busid */
int unique_len; /**< Length of unique field */
+ int unique_size; /**< amount allocated */
int blocked; /**< Blocked due to VC switch? */