[PATCH 3.8 56/91] drm: Prevent overwriting from userspace underallocating core ioctl structs

From: Kamal Mostafa
Date: Thu Nov 07 2013 - 21:23:26 EST


3.8.13.13 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>

commit b062672e305ce071f21eb9e18b102c2a430e0999 upstream.

Apply the protections from

commit 1b2f1489633888d4a06028315dc19d65768a1c05
Author: Dave Airlie <airlied@xxxxxxxxxx>
Date: Sat Aug 14 20:20:34 2010 +1000

drm: block userspace under allocating buffer and having drivers overwrite it (v2)

to the core ioctl structs as well, for we found one instance where there
is a 32-/64-bit size mismatch and were guilty of writing beyond the end
of the user's buffer.

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Reviewed-by: Ville SyrjÃlà <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_drv.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index be174ca..4177780 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -411,9 +411,16 @@ long drm_ioctl(struct file *filp,
asize = drv_size;
}
else if ((nr >= DRM_COMMAND_END) || (nr < DRM_COMMAND_BASE)) {
+ u32 drv_size;
+
ioctl = &drm_ioctls[nr];
- cmd = ioctl->cmd;
+
+ drv_size = _IOC_SIZE(ioctl->cmd);
usize = asize = _IOC_SIZE(cmd);
+ if (drv_size > asize)
+ asize = drv_size;
+
+ cmd = ioctl->cmd;
} else
goto err_i1;

--
1.8.1.2

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